Liquid Barrier Nonwoven Fabrics with Ribbon-Shaped Fibers

ABSTRACT

A nonwoven fabric useful as a component in a personal hygiene product and a nonwoven personal hygiene component, which is substantially free or free of non-ribbon shaped (e.g., round-shaped) spunbond fibers and includes a meltblown layer between and in direct contact with ribbon-shaped spunbond layers. The meltblown layer has a basis weight of at least about 0.008 gsm and not greater than about 5 gsm, and the nonwoven fabric or component has a basis weight of at least about 8 gsm and not greater than about 40 gsm, a pore size of less than or equal to about 27 microns when measured at 10% of cumulative filter flow. The nonwoven fabric also can have a low surface tension liquid strike through flow of less than 0.9 ml per second, a ratio of low surface tension liquid strike through flow to air permeability of greater than or equal to about 0.016, or both. Personal hygiene articles can incorporate the nonwoven fabric or component.

FIELD OF INVENTION

The present invention relates to fibrous nonwoven fabrics that areuseful as liquid barrier fabrics in personal hygiene products, and,particularly, nonwoven fabrics that include ribbon-shaped spunbondlayers that are in direct contact with at least one interveningmeltblown layer. Nonwoven fabrics of this invention exhibit enhanced lowsurface tension liquid resistance and air permeability.

BACKGROUND

Nonwoven absorbent articles, such as disposable diapers, training pants,incontinent wear, and feminine hygiene products, have used nonwovenfabrics for many purposes, such as liners, transfer layers, absorbentmedia, backings, and the like. For many such applications, the barrierproperties of the nonwoven can serve a significant function. Forexample, U.S. Pat. No. 5,085,654 to Buell discloses disposable diapersprovided with breathable leg cuffs that are formed from material, suchas thermoplastic films, which allows passage of vapor while tending toretard the passage of liquid. Buell discloses a cuff having a breathableportion that is different in character from an impermeable portion ofthe cuff.

Nonwoven fabrics that include fibers or filaments having differentcross-sectional shapes have also been disclosed. For example, UnitedStates Patent Publ. No. 2005/0215155 A1 to Young et al. discloses inpart a laminate comprising a first nonwoven layer comprising firstcontinuous filaments, a second nonwoven layer comprising secondcontinuous filaments, and a third nonwoven layer comprising fine fibers,wherein the first and second continuous filaments have cross-sectionalshapes that are distinct from one another.

U.S. Pat. No. 6,471,910 to Haggard et al. discloses a nonwoven fabricformed from a spunbond process by extruding generally ribbon-shapedfibers as defined therein through slot-shaped orifices of a spinneret.Haggard et al. discloses nonwoven webs or fabrics composed solely of theribbon-shaped fibers as defined therein and discloses the fibers can beused in combination with fibers of other transverse cross-sections andin combination with other technologies to form composite materials, suchas meltblown or film composites without illustration or reference to alaminate having a structure of two spunbond layers surrounding ameltblown layer or specific improved low surface tension liquidresistance or air permeability.

United States Patent Publ. No. 2005/0227563 A1 to Bond discloses afibrous fabric including at least one layer comprising a mixture ofshaped fibers having two or more different cross-sections. Bonddiscloses a laminate with at least one first layer comprising a mixtureof shaped fibers having cross-sectional shapes that are distinct fromone another and at least one second layer comprising different fibersthat are not identical in cross-sectional shape and ratio to the fibersin the first layer.

U.S. Pat. No. 7,309,522 to Webb et al. discloses fibers, elastic yarns,wovens, nonwovens, knitted fabrics, fine nets, and articles producedfrom fibers comprising a styrenic block copolymer. Webb et al. disclosesthe shape of the fiber can vary widely, wherein a typical fiber has acircular cross-sectional shape, but sometimes fibers have differentshapes, such as tri-lobal shape, or what is said to be a flat ‘ribbon’like shape, which may be included in a three layerspunbond-meltblown-spunbond “sandwich”. Webb et al. does not disclosethe improvement of low surface tension liquid resistance or airpermeability.

U.S. Pat. No. 5,498,468 to Blaney discloses a method of making aflexible fabric composed of a fibrous matrix of ribbon-like, conjugate,spun filaments. Blaney discloses applying a flattening force to thefibrous matrix to durably distort the core of individual filaments intoa ribbon-like configuration as characterized in the reference. Blaneyalso discloses a method that includes drawing the extruded conjugatefilaments as they are being quenched and applying a flattening force todurably distort the core of individual filaments into a ribbon-likeconfiguration of the reference.

United States Patent Publ. No. 2006/0012072 A1 to Hagewood et al.discloses a fibrous product including a mixture of different shapedfibers that are formed using a spin pack assembly including a spinneretwith at least two spinneret orifices having different cross-sections.Hagewood et al. shows a fibrous web containing a mixture ofmulticomponent solid round, monocomponent trilobal fibers, and meltblownfibers in examples.

U.S. Pat. No. 6,613,704 B1 to Arnold et al. discloses nonwoven webs ofcontinuous filaments having a mixture or blend of first and secondcontinuous filaments, wherein the second continuous filaments aredifferent from the first continuous filaments in one or more respectssuch as size, cross-sectional shape, polymer composition, crimp level,wettability, liquid repellency, and charge retention. Arnold et al.discloses that the second continuous filaments can be substantiallysurrounded by the first continuous filaments wherein the ratio of firstcontinuous filaments to second continuous filaments exceeds about 2:1.

Resistance to low surface tension liquid strike through andbreathability are performance characteristics of liquid barrier fabrics.Liquid strike through generally refers to the permeability of liquidthrough the fabric and breathability generally refers to thepermeability to air and vapor through the fabric.

The present inventors have recognized that there is a need for a fabricthat can be used in personal hygiene products that achieves asynergistic balance of low surface tension liquid strike through andbreathability with unique combinations of fibers and nonwoven fibrouslayers having different structures.

SUMMARY

A nonwoven fabric usable as a component in a personal hygiene product isprovided which includes a first ribbon-shaped spunbond layer, a secondribbon-shaped spunbond layer and a meltblown layer disposed between thefirst and second ribbon-shaped spunbond layers. The meltblown layer isin direct contact with the first and second ribbon-shaped spunbondlayers. As an option, the meltblown layer can include multiple directlyadjoining meltblown sub-layers, which can be present as a stack, whereinthe two outer sides of the stack are in direct contact with the firstand second ribbon-shaped spunbond layers, respectively. As an option,one or more of the first ribbon-shaped spunbond layer, the secondribbon-shaped spunbond layer and the meltblown layer comprisespolypropylene, as defined herein. The meltblown layer comprisesmeltblown fibers in an amount of at least 0.1% by weight of the nonwovenfabric and not greater than about 40% by weight of the nonwoven fabric,and the meltblown layer has a basis weight no greater than 5 gsm. Thenonwoven fabric is substantially free or free of non-ribbon shapedspunbond fibers (e.g., round-shaped spunbond fibers). The nonwovenfabric has a basis weight of at least about 8 grams/m² (gsm) and notgreater than about 40 gsm and a pore size measured at 10% of cumulativefilter flow of no more than about 27 microns.

As an option, the nonwoven fabric can contain round-shaped spunbondfilaments in an amount of less about 10% by weight, or less than about5% by weight, or less than about 1% by weight, or 0% by weight to about10% by weight, or lesser range amounts, such as disclosed herein, withrespect to the entire nonwoven fabric. As another option, the first andsecond ribbon-shaped spunbond layers comprise fibers having across-section with an aspect ratio greater than about 1.5:1, or fromabout 1.55:1 to about 7:1, or from about 1.6:1 to about 7:1, or fromabout 1.75:1 to about 7:1, or from about 2.5:1 to about 7:1, or othervalues such as disclosed herein. As another option, the nonwoven fabrichas a pore size measured at 25% of cumulative filter flow of less thanabout 23 microns.

As another option, the nonwoven fabric has an air permeability of atleast about 10 m³/m²/min or other values such as disclosed herein. Asanother option, the nonwoven fabric can have a low surface tensionliquid strike through flow of less than 0.9 ml per second, or less than0.8 ml per second, or other values such as disclosed herein. As anotheroption, the meltblown layer of the nonwoven fabric has a basis weight ofat least about 0.3 gsm and no greater than about 5 gsm, or at leastabout 0.4 gsm and no greater than about 4 gsm, or at least about 0.7 gsmand no greater than about 2 gsm, or other values such as disclosedherein. As another option, the nonwoven fabric has a basis weight of atleast about 8.5 gsm and not greater than about 30 gsm, or at least about11 gsm and not greater than about 25 gsm, or other values such asdisclosed herein. As another option, the first and second spunbondlayers and the meltblown layer are bonded together by a plurality ofdiscrete bond areas. As another option, the discrete bond areas can bethermal bonds formed as a plurality of bond points wherein the pluralityof bond points comprise up to about 25% of the surface area of nonwovenfabric, such as from about 10% to about 25% of the surface area of thenonwoven fabric, or other percentages such as disclosed herein.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory onlyand are intended to provide a further explanation of the presentinvention, as claimed.

The accompanying drawings, which are incorporated in and constitute apart of this application, illustrate some of the embodiments of thepresent invention and together with the description, serve to explainthe principles of the present invention. Features having the samereferencing numeral in the various figures represent similar elementsunless indicated otherwise. The figures and features depicted thereinare not necessarily drawn to scale.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of a nonwoven fabric useable in a personalhygiene product in accordance with an embodiment of the invention.

FIG. 2 is a schematic diagram of a forming system used to make anonwoven fabric in accordance with an embodiment of the presentinvention.

FIGS. 3A-F illustrate cross-sectional enlarged views of severaldifferent shapes of fibers, wherein FIGS. 3A-E showing variousribbon-shaped fibers in accordance with embodiments of the presentinvention.

FIG. 4 is a fragmentary perspective view, with sections broken away, ofa nonwoven fabric in accordance with an embodiment of the presentinvention.

FIG. 5 is a sectional view along line 4-4 of FIG. 4.

FIG. 6 illustrates the correlation between the difference in Flow Ratioand the difference in pore size at 10% cumulative filter flow forspunbond/meltblown/meltblown/spunbond (S/M/M/S) nonwoven fabrics madewith ribbon-shaped spunbond fibers and round-shaped spunbond fibers, inaccordance with descriptions in the Examples section herein.

FIG. 7 illustrates the correlation between the difference in Flow Ratioand the difference in pore size at 25% cumulative filter flow forspunbond/meltblown/meltblown/spunbond (S/M/M/S) nonwoven fabrics madewith ribbon-shaped spunbond fibers and round-shaped spunbond fibers inaccordance with descriptions in the Examples section herein.

DEFINITIONS

As used herein, the term “fiber(s)” generally can refer to continuousfilaments, substantially continuous filaments, staple fibers, and otherfibrous structures having a fiber length that is substantially greaterthan its cross-sectional dimension(s).

As used herein, the term “continuous filament(s)” refers to a polymerstrand or polymer fiber that is not broken during the regular course offormation.

As used herein, the term “fine fiber(s)” refers to discrete polymerfibers or strands with an average dimension dl, as defined herein, notto exceed about 10 μm.

As used herein, the term “ribbon-shaped” refers to a cross-sectionalgeometry and aspect ratio. With respect to the cross-sectional geometry,“ribbon-shaped” refers to a cross-section that includes at least onepair (set) of symmetrical surfaces. For example, the cross section canbe a polygon which includes two different pairs of opposite symmetricalsurfaces or only one set thereof. For example, with reference to FIG. 3Afor sake of illustration and not limitation, the overall shape 35 has animaginary major bisector 300, and a minor bisector (not shown), which isperpendicular to the major bisector, wherein opposite surfaces 351 and352 are symmetrical surfaces with respect to each other with referenceto the imaginary bisector 300. Other ribbon-shape geometries having atleast one set of symmetrical surfaces are illustrated, for example, inFIGS. 3B-3E. The major bisector 300 can be straight (e.g., FIGS. 3A-3D),curvilinear (e.g., FIG. 3E), or other shapes, depending on thecross-sectional shape of the fiber. “Ribbon-shaped” can include, forexample, a shape having two sets of parallel surfaces forming arectangular shape (e.g. FIG. 3A). “Ribbon-shaped” can also include, forexample, a cross-section having one set of parallel surfaces, which canbe joined to one another by shorter rounded end joints having a radiusof curvature (e.g., FIG. 3B). “Ribbon-shaped” additionally can include,for example, “dog-bone” shaped cross-sections, such as illustrated inFIG. 3C, and oval or elliptical shaped cross-sections, such asillustrated in FIG. 3D. In these cross-sections illustrated in FIGS. 3Cand 3D, the term “ribbon-shaped” refers to a cross-section that includessets of symmetrical surfaces which comprise rounded (e.g. curvilinear orlobed) surfaces, that are oppositely disposed. As illustrated in FIG.3D, the oval shaped cross-sections can have rounded or curvilinear typetop and bottom symmetrical surfaces, which are joined to one another byshorter rounded end joints at the sides having a relatively smallerradius of curvature than the top and bottom symmetrical surfaces. Theterm “ribbon-shaped” also includes cross-sectional geometry thatincludes no more than two square ends, or round ends, or “lobes” alongthe perimeter of the cross-section. FIG. 3C, for example, shows abi-lobal cross-section. The lobes differ from the indicated rounded endjoints included in the cross-sections such as shown in FIGS. 3B and 3Dreferred to above. Surface irregularities like bumps or striations orembossed patterns that are relatively small when compared to theperimeter of the cross-section, or are not continuous along the lengthof the fibers are not included in the definition of “lobes,” or therounded end joints. It can also be understood that the above definitionof “ribbon-shaped” covers cross-sectional geometries in which one ormore of the sets of surfaces (e.g., the opposite lengthwise surfaces)are not straight (e.g. FIG. 3E), provided such cross-sectionalgeometries meet the aspect ratio requirements as defined below.

With respect to aspect ratio, a “ribbon-shaped” cross-section has anaspect ratio (AR) of greater than 1.5:1. The aspect ratio is defined asthe ratio of dimension d1 and dimension d2. Dimension d1 is the maximumdimension of a cross-section, whether ribbon-shaped or otherwise,measured along a first axis. Dimension d1 is also referred to as themajor dimension of the ribbon-shaped cross-section. Dimension d2 is themaximum dimension of the same cross-section measured along a second axisthat is perpendicular to the first axis that is used to measuredimension d1, where dimension d1 is greater than dimension d2. Dimensiond2 is also referred to as the minor dimension. As an option, the majorbisector 300 can lie along the first axis and the minor bisector (notshown) can lie along the second axis. Examples of how dimensions d1 andd2 are measured are illustrated in FIGS. 3A, 3B, 3C, 3D, and 3E, whichillustrate ribbon-shaped cross-sections and in FIG. 3F which illustratesa non-ribbon-shaped cross-section as described below. Aspect ratio iscalculated from the normalized ratio of dimensions d1 and d2, accordingto formula (1):

AR=(d1/d2):1  (1)

-   The units used to measure d1 and d2 are the same.

The term “ribbon-shaped” excludes for example, cross-sectional shapesthat are round, circular or round shaped as defined herein. As referredto herein, the terms “round”, “circular” or “round-shaped” refer tofiber cross-sections that have an aspect ratio or roundness of 1:1 to1.5:1. An exactly circular or round fiber cross-section has an aspectratio 1:1 which is less than 1.5:1. Any fiber that does not meet theindicated criteria for “ribbon-shaped” fiber as defined herein is“non-ribbon shaped”. Other non-ribbon shaped fibers include, forexample, square, tri-lobal, quadri-lobal, and penta-lobalcross-sectional shaped fibers. For example, a square shapedcross-section has an aspect ratio of 1:1 which is less than 1.5:1. Atri-lobal cross-section fiber, for example, has three round ends or“lobes”, and thus does not meet the definition for “ribbon-shaped”cross-section. Illustrations of some of these shapes and the manners ofevaluating the aspect ratios thereof in accordance with embodiments areincluded herein.

As used herein, a “nonwoven(s)” refers to a fiber-containing materialwhich is formed without the aid of a textile weaving or knittingprocess.

As used herein, the terms “nonwoven fabric” or “nonwoven component” maybe used interchangeably and refer to a nonwoven collection of polymerfibers or filaments in a close association to form one or more layers,as defined herein. The one or more layers of the nonwoven fabric ornonwoven component can include staple length fibers, substantiallycontinuous or discontinuous filaments or fibers, and combinations ormixtures thereof, unless specified otherwise. The one or more layers ofthe nonwoven fabric or nonwoven component can be stabilized orunstabilized.

As used herein, the term, “spunmelt” refers to methods of producingnonwovens by extruding polymer into fibers or filaments and bonding thefibers or filaments thermally, chemically, or mechanically.

As used herein, the term “absorbent article(s)” refers to devices thatabsorb and contain liquid, and more specifically, refers to devices thatare placed against or in proximity to the body of the wearer to absorband contain the various exudates discharged from the body.

As used herein, the term, “personal hygiene product” refers to any itemthat can be used to perform a personal hygiene function or contribute toa hygienic environment of an individual. Personal hygiene products ofthe invention include, but are not limited to, diapers, training pants,absorbent underpants, incontinence articles, feminine hygiene products(e.g., sanitary napkins), medical protective barrier articles, such asgarments and drapes, sterilization wraps and foot covers.

The term “personal hygiene component” refers to a nonwoven component ofa personal hygiene product, for example, a leg cuff used in a diaper,training pants, absorbent underpants or incontinence article, or othersegment of a feminine hygiene product, or medical protective barrierarticle are personal hygiene components.

The term “dimension” is a measurement of the cross-section of the fibersdescribed herein. In instances where the fiber has a round or circularcross-section, the dimension of the fiber will be the same as thediameter of the fiber.

The term “spunbond” or “S” may be used interchangeably with “continuousfilament(s) or fiber(s)” and refers to fibers or filaments which areformed by extruding a molten material as filaments from a plurality offine capillaries in a spinneret, and the dimension of the extrudedfilaments then may be reduced by drawing or other known methods. Theterm “spunbond” also includes fibers that are formed as defined above,and which are then deposited or formed in a layer in a single step.

The term “meltblown” or “M” may be used interchangeably with “finefibers” or “discontinuous fibers” and refers to fibers formed byextruding a molten material and drawing the extruded molten materialwith high-velocity fluid into fibers having dimension dl, as definedherein, of less than 10 microns, or more specifically less than 5microns or even more specifically, less than 2 microns. The term“meltblown” also includes fibers that have a round cross-sectionalgeometry and an aspect ratio of less than 1.5:1. The term “meltblown”also includes fibers that are described as not continuous, in contrastto spunbond fibers. The term “meltblown” also includes fibers formed bya process in which molten material is extruded through a plurality offine die capillaries into a high-velocity gas stream which attenuatesthe fibers of molten material to reduce their dimensions to a dimensiond1 of less than about 10 microns or, more specifically, a dimension d1of less than about 3 microns.

As used herein, a “sub-layer” is defined as similar material or similarcombination of materials formed from a single production beam, whereinthe material exists in at least one major plane (e.g., an X-Y plane)with a relatively smaller thickness extending in the orthogonaldirection thereto (e.g., in a Z direction thereto). The fibers of asub-layer, for example, may include only spunbond fibers, only meltblownfibers or only a single type of fibers. As used herein, a “layer” isdefined as one or more sub-layers comprising fibers made from the sameresin and fibers that are defined as the same type of fiber (e.g., onlyspunbond, only meltblown or only another type of fiber).

The term “component” is used herein to refer to a segment or portion ofan article or product.

As used herein, a “laminate” generally refers to at least two joinedtogether nonwoven layers contacting along at least a portion ofadjoining faces thereof with or without interfacial mixing.

As used herein, “substantially free,” as used with respect to thecontent of round-shaped fibers in a nonwoven fabric, refers to less than10% by weight based on the total weight of the nonwoven fabric.

As used herein, “comprising” or “comprises” is synonymous with“including,” “containing,” “having”, or “characterized by,” and isopen-ended and does not exclude additional, unrecited elements or methodsteps, and thus should be interpreted to mean “including, but notlimited to . . . ”.

As used herein, “consisting of” excludes any element, step, oringredient not specified.

As used herein, “consisting essentially of”, refers to the specifiedmaterials or steps and those that do not materially affect the basic andnovel characteristic(s) of the nonwoven fabrics of the invention asdescribed herein.

DETAILED DESCRIPTION

The present invention is directed to a nonwoven fabric usable as acomponent in a personal hygiene product. The nonwoven fabric has atleast one meltblown layer disposed between and in direct contact withribbon-shaped spunbond layers. The nonwoven fabric is at leastsubstantially free of non-ribbon shaped spunbond fibers (e.g.,round-shaped spunbond fibers), such as less than 10% by weight of thefabric is non-ribbon shaped spunbond fiber.

Improved Performance Characteristics of Nonwoven Fabric

A benefit of this invention, and such as shown in the examples, is theprovision of better resistance to low surface tension liquid whencompared to a nonwoven fabric of similar general construction but madefrom round-shaped spunbond fibers in the spunbond layers. Further,nonwoven fabrics have been developed in the present invention which canbe used, for example, as a barrier layer in a diaper or other personalhygiene products that have synergistic barrier properties whenencountering low surface tension liquids of types which are commonlyencountered in such uses, while being air and moisture vapor breathableand manufacturable at low cost. Breathability is an importantconsideration as air and vapor movement through the fabric is associatedwith wearer comfort. The nonwoven fabrics of the present invention canprovide enhanced breathability without compromising liquid barrierproperties.

It has been found that examples of similar nonwoven fabric constructioncomprising meltblown fibers and spunbond fibers that are round-shapedperform differently than those that are ribbon-shaped in regard to airpermeability and resistance to penetration by low surface tension liquid(referred to herein as “LSTST-Flow”). It has been observed, for example,that the ratio of LSTST-Flow to air permeability (referred herein as“Flow Ratio”) can be affected by the selected materials and design ofthe nonwoven fabric and fibers in previously unrecognized manners. Ithas been demonstrated, for example, that there is a superior range ofconstruction involving a synergistic combination of meltblown fibers andribbon-shaped spunbond fibers in adjoining layers, wherein theresistance to liquid flow can be increased with less reduction in airpermeability. It has been found, for example, that the use ofribbon-shaped spunbond fibers in spunbond layers that sandwich meltblownlayer(s) having a restricted total content of meltblown fibers, whereinthe meltblown fiber web formation is designed to have provide a nonwovenfabric with a pore size measured at 10% of cumulative filter flow of nomore than about 27 microns and/or a pore size measured at 25% cumulativefilter flow of less than 23 microns, can yield unique beneficial effectson the breathability and liquid barrier properties of the nonwovenfabric.

As an option, a nonwoven fabric that has a reduced Flow Ratio can beprovided, which includes a meltblown layer or meltblown layers having atotal basis weight of at least about 0.008 gsm and no greater than about5 gsm, as sandwiched between spunbond layers comprising ribbon-shapedspunbond fibers in a nonwoven fabric that has a total basis weight of atleast about 8 gsm and not greater than about 40 gsm.

As an option, a nonwoven fabric is provided that has an air permeabilityof at least about 9 m³/m²/min, or at least about 10 m³/m²/min, or atleast about 15 m³/m²/min, or at least about 20 m³/m²/min, or at leastabout 25 m³/m²/min, or at least about 30 m³/m²/min, or at least about 35m³/m²/min, or at least about 40 m³/m²/min, or at least about 45m³/m²/min, or at least about 50 m³/m²/min, or greater values. As anoption, a nonwoven fabric is provided that has an air permeability of atleast about 9 m³/m²/min to no greater than 140 m³/m²/min, or at leastabout 12 m³/m²/min to no greater than about 130 m³/m²/min, or at leastabout 15 m³/m²/min to no greater than about 120 m³/m²/min, or at leastabout 20 m³/m²/min to no greater than about 110 m³/m²/min, or at leastabout 25 m³/m²/min to no greater than about 100 m³/m²/min, or at leastabout 30 m³/m²/min to no greater than about 95 m³/m²/min, or at leastabout 40 m³/m²/min to no greater than about 90 m³/m²/min, or at leastabout 45 m³/m²/min or no greater than about 85 m³/m²/min, or at leastabout 50 m³/m²/min to no greater than about 80 m³/m²/min, or otherranges within these values.

As another benefit of these constructions, the nonwoven fabric can havea LSTST-Flow of less than 0.9 ml per second, or less than 0.8 ml persecond, or less than 0.7 ml per second, or less than 0.6 ml per second,or less than 0.5 ml per second, or less than 0.4 ml per second, or lessthan 0.3 ml per second, or lower range values.

As a further option, a nonwoven fabric is provided that has a Flow Ratioof less than or equal to about 0.06, or less than or equal to about0.058, or less than or equal to about 0.056, or less than or equal toabout 0.054, or less than or equal to about 0.052, or less than or equalto about 0.05, or less than or equal to about 0.048, or less than orequal to about 0.046, or less than or equal to about 0.044, or less thanor equal to about 0.042, or less than or equal to about 0.04, or lessthan or equal to about 0.038, or less than or equal to about 0.036, orless than or equal to about 0.034, or less than or equal to about 0.032,or less than or equal to about 0.030, or less than or equal to about0.028, or less than or equal to about 0.026, or less than or equal toabout 0.024, or less than or equal to 0.023, or less than or equal to0.022, or lesser range values, or from at least about 0.015 to nogreater than about 0.06, or from at least about 0.015 to no greater thanabout 0.058, or from at least about 0.015 to no greater than about0.056, or from at least about 0.015 to no greater than about 0.054, orfrom at least about 0.015 to no greater than about 0.052, or from atleast about 0.015 to no greater than about 0.050, or from at least about0.018 to no greater than about 0.04, or from at least about 0.018 to nogreater than about 0.035, or from at least about 0.018 to no greaterthan about 0.030, from at least about 0.018 to no greater than about0.025, or from at least about 0.019 to no greater than about 0.025, orfrom at least about 0.019 to no greater than about 0.024, from at leastabout 0.019 to no greater than about 0.023, or at least about 0.019 tono greater than about 0.022 or other ranges within these values. Asanother benefit of these constructions, any of these reduced LSTST-Flowto air permeability ratios can be provided in a nonwoven fabric of thepresent invention which has a pore size measured at 10% of cumulativefilter flow of no more than about 27 microns or at 25% cumulative filterflow of no more than 23 microns. As another option, any of these reducedFlow Ratios can be provided in a nonwoven fabric of the presentinvention which has a pore size measured at 10% of cumulative filterflow of no more than about 25 microns, or no more than 23 microns or nomore than 21 microns.

Nonwoven Fabric Structure

FIG. 1 illustrates a nonwoven fabric of an option of the presentinvention in a perspective view with cut-aways to show detail. The threeor four layer nonwoven fabric 10 shown in FIG. 1 can be created from theforming machine described with respect to FIG. 2 herein. In FIG. 1, thenonwoven fabric 10 has a first ribbon-shaped spunbond layer 12 of firstribbon-shaped spunbond fibers 13 (e.g., continuous spunbond filaments),a meltblown layer 14 of meltblown fibers 15, and a second ribbon-shapedspunbond layer 16 of second ribbon-shaped spunbond fibers 17 (e.g.,continuous spunbond filaments). As illustrated in FIG. 1, the firstribbon-shaped spunbond layer 12, meltblown layer 14, and secondribbon-shaped spunbond layer 16 are in direct contact with therespective adjoining layer or layers to each of them. As used herein,the wording “direct contact” between a ribbon-shaped spunbond layer (12or 16) and a meltblown layer 14, or between meltblown sub-layers 14A and14B if used, can mean that at least about 50%, or at least about 60%, orat least about 70%, or at least about 80%, or at least about 90%, or atleast about 95%, or at least about 99%, or 100%, of the surfaces areasof the adjacent faces of the two respective layers are in physicalcontact with each other (e.g., contact areas are free of interposeddifferent materials or air pockets that space the surfaces of theadjoining layers apart).

The first ribbon-shaped spunbond layer 12 comprised of firstribbon-shaped spunbond fibers 13 can have a basis weight, for example,of at least about 3.9 gsm and not greater than about 19.5 gsm, or atleast 4.1 gsm and not greater than about 13 gsm, or at least about 5.1gsm and not greater than about 11.5 gsm, or at least about 5 gsm and notgreater than about 6.5 gsm, or at least about 5.5 gsm and no greaterthan about 6.25 gsm or other ranges amounts within these ranges. Asanother option, the first ribbon-shaped spunbond layer 12 comprised offirst ribbon-shaped spunbond fibers 13 can have a basis weight, forexample, 6 gsm. As an option, the first ribbon-shaped spunbond layer 12can comprise first ribbon-shaped spunbond fibers 13 with denier (g/9,000m) in the range, for example, of from about 1.0 to about 4.0, or fromabout 1.0 to about 3.5, or from about 1.0 to about 3.2, or from about1.0 to about 2.8, or from about 1.0 to about 2.4, or from about 1.0 toabout 2.0, or other denier values. As another option, the firstribbon-shaped spunbond layer 12 can comprise first ribbon-shapedspunbond fibers 13 having an average dimension d1 of greater than about12.5 μm, or from about 12.5 μm to about 50 μm, or from about 12.5 μm toabout 40 μm, or from about 12.5 μm to about 30 μm, or from about 12.5 μmto about 28 μm, or other values. The dimension d1 can be determined, forexample, as part of the aspect ratio measurements which are described inthe examples section herein.

As indicated, the first ribbon-shaped spunbond fibers 13 can havecross-sectional shapes including, but not limited to, shapes selectedfrom the group consisting of flat, oval, bi-lobal, rectangular, and anycombinations thereof. As an option, the first ribbon-shaped spunbondfibers 13 can all have the same cross-sectional geometry (e.g., allrectangular, or all bi-lobal, or all flat, or all oval) with respect toeach other within the indicated required range for ribbon-shaped fibers.As another option, the first ribbon-shaped spunbond fibers 13 can havethe same or different aspect ratios with respect to each other withinthe indicated required range for ribbon-shaped fibers. As anotheroption, the first ribbon-shaped spunbond fibers can have the samecross-sectional geometry and the same aspect ratio with respect to eachother, with both the cross-sectional geometry and aspect ratio beingwithin the indicated required range for ribbon-shaped fibers. Forexample, the first ribbon-shaped spunbond fibers 13 can all compriserectangular cross-sectional geometry, wherein the aspect ratio is 2:1for all of the fibers. As another option, the first ribbon-shapedspunbond fibers can have the same cross-sectional geometry but differentaspect ratio with respect to each other. For example, the firstribbon-shaped spunbond fibers 13 can have the same rectangularcross-section while the aspect ratio first ribbon-shaped spunbond fibers13 can vary, e.g., in a range from about 1.75:1 to about 2.25:1, orother aspect ratio values within the indicated required criterion (i.e.,AR>1.5:1). Where the aspect ratios may vary, the denier of the firstribbon-shaped spunbond fibers also can vary.

The nonwoven fabric 10 further comprises a second ribbon-shaped spunbondlayer 16 which is comprised of second ribbon-shaped spunbond fibers 17.The second ribbon-shaped spunbond layer 16 can have a basis weight inthe ranges indicated for the first ribbon-shaped spunbond layer 12. Asoptions, the second ribbon-shaped spunbond fibers 17 in the secondribbon-shaped spunbond layer 16 can have cross-sectional geometries,aspect ratios, denier, dimension d1 values, average dimension d1 valuesand combinations thereof that are similar to that indicated for thefirst ribbon-shaped spunbond fibers 13 of the first ribbon-shapedspunbond layer 12. As an option, the second ribbon-shaped spunbondfibers 17 may have the same cross-sectional geometry and the same aspectratio with respect to each other. As another option, the secondribbon-shaped spunbond fibers can have the same cross-sectional geometrybut different aspect ratio with respect to each other.

As an option, the cross-sectional geometry and/or aspect ratios selectedand used for the first and second ribbon-shaped spunbond fibers 13 and17 in one of the first and second ribbon-shaped spunbond layers 12 and16, respectively, can be the same with respect to the otherribbon-shaped spunbond layer (12 or 16). For example, as an option, boththe first and second ribbon-shaped spunbond layers 12 and 16 can containribbon-shaped spunbond fibers 13 and 17, respectively, havingrectangular cross-sectional geometries and/or similar aspect ratios withrespect to each other. Alternatively, one of the first and secondribbon-shaped spunbond layers 12 and 16 can include ribbon-shapedspunbond fibers 13 and 17, respectively, with different aspect ratiosfrom the ribbon-shaped spunbond fibers (13 or 17) of the other of thefirst and second ribbon-shaped spunbond layers (12 or 16). As yetanother option, the first spunbond layer 12 has first ribbon-shapedspunbond fibers 13 with a mixture of aspect ratios of, while the secondspunbond layer 16 has second ribbon-shaped fibers 17 having a singleaspect ratio or a different mixture of aspect ratios than the firstribbon-shaped spunbond fibers 13.

As an option, the number of different aspect ratios of the ribbon-shapedspunbond fibers allowed in a single ribbon-shaped spunbond layer iscontrolled. As an option, each of the first ribbon-shaped spunbond layer12 and second ribbon-shaped spunbond layer 16 can comprise similarribbon-shaped spunbond fibers with respect to aspect ratios in an amountof at least about 90% by weight, or at least about 91% by weight, or atleast about 92% by weight., or at least about 93% by weight, or at leastabout 94% by weight, or at least about 95% by weight, or at least about96% by weight, or at least about 97% by weight., or at least about 98%by weight, or at least about 99% by weight, or 100% by weight, of thetotal fiber content of each respective ribbon-shaped spunbond layer.

The nonwoven fabric 10 can include more than two ribbon-shaped spunbondlayers. As an option, the additional ribbon-shaped spunbond layers caninclude ribbon-shaped spunbond fibers having the same or differentcross-sectional geometries and/or aspect ratios as the first and/orsecond ribbon-shaped fibers 13 or 17 as described herein. The additionalribbon-shaped spunbond layers can be disposed to be in direct contactwith either the first or second ribbon-shaped spunbond layers 12 or 16,respectively. It will be understood that the total amount of theribbon-shaped spunbond fibers in the additional ribbon-shaped spunbondlayers will be consistent with basis weights and basis weightpercentages disclosed herein. As an option, the nonwoven fabric 10excludes non-ribbon shaped spunbond fibers.

As also indicated in FIG. 1, the nonwoven fabric 10 comprises ameltblown layer 14 which itself is comprised of meltblown fibers 15. Themeltblown layer 14 can have a basis weight, for example, of from atleast about 0.008 gsm to no greater than about 5 gsm, or from at leastabout 0.4 gsm to no greater than about 4 gsm, or from at least about 0.7gsm to no greater than about 2 gsm, or from at least about 1.0 gsm to nogreater than about 2 gsm, or from at least about 1.1 gsm to no greaterthan about 1.7 gsm, or from at least about 1.2 gsm to no greater thanabout 1.4 gsm or from at least about 0.5 gsm to no greater than about 4gsm, or from at least about 0.6 gsm to no greater than about 3 gsm, orother values within these ranges. As an option, the meltblown layer 14can comprise meltblown fibers 15 having an average dimension d1 thatdoes not exceed about 10 μm, or does not exceed about 7.5 μm, or doesnot exceed about 5 μm, or does not exceed 3 μm or does not exceed 1.8μm, or is from about 0.3 to about 10 μm, or is from about 1 to about 10μm, or is from about 1 to about 7.5 μm, or is from about 0.5 to about 5μm, or other ranges within these values. As an option, two or moremeltblown sub-layers 14A and 14B of meltblown fibers 15A and 15B can beused to form the meltblown layer 14 and can be disposed between firstand second ribbon-shaped spunbond layers 12 and 16, respectively. Themeltblown sub-layers 14A and 14B, if used, can have an interface 140,which is indicated by the dashed line in FIG. 1. One meltblown sub-layer14B can be provided in direct contact with the second meltblownsub-layer 14A. Although one or two meltblown layers are illustrated inFIG. 1 as used in nonwoven fabric 10, additional meltblown sub-layers(e.g., three, four, etc.) can be disposed between the ribbon-shapedspunbond layers 12 and 16, respectively.

Where multiple directly adjoining meltblown sub-layers are present as astack 141, such as illustrated by sub-layers 14A and 14B, the two outersides 142 and 143 of the stack 141 are in direct contact with the firstand second ribbon-shaped spunbond layers 12 and 16, respectively. As anoption, if three or more meltblown sub-layers are used (not shown), thetwo outermost meltblown sub-layers of the stack can have an outer sidethat directly contacts an adjoining ribbon-shaped spunbond layer (12 or16) and an inner side in contact with the middle or intermediatemeltblown sub-layer or layers of the same stack, which are spaced fromthe ribbon-shaped spunbond layers (12 and 16). If two or more meltblownsub-layers are used, then the previously described meltblown basisweights apply to combined total basis weights of the two or moremeltblown sub-layers or to the whole meltblown layer 14 made from thevarious meltblown sub-layers. For example, if three meltblown sub-layersare used, the total combined basis weight of the three meltblownsub-layers can be, for example, from at least about 0.008 gsm to nogreater than about 5 gsm, or the other indicated ranges. The meltblownsub-layers 14A and 14B, if used, can have similar fiber and web featuresand materials as described for the meltblown layer 14, however, theindicated calculation of meltblown sub-layer basis weights will be basedon their combined values. As illustrated in FIG. 1, the firstribbon-shaped spunbond layer 12, the meltblown sub-layers 14A and 14B ormeltblown layer 14, and the second ribbon-shaped spunbond layer 16 arein direct contact with their adjoining layer or layers. In an option,the meltblown layer 14, or meltblown sub-layers 14A and 14B if used,comprise fine fibers in amount of at least about 80% by weight, or atleast 85% by weight, or at least 90% by weight, or at least 91% byweight, or at least 92% by weight, or at least 93% by weight, or atleast 94% by weight, or at least 95% by weight, or at least 96% byweight, or at least 97% by weight, or at least 98% by weight, or atleast 99% by weight, or 100% by weight, based on the total basis weightof the meltblown layer 14 or each respective meltblown sub-layer 14A and14B, as applicable.

The resultant nonwoven fabric 10 has the meltblown layer 14 (ormeltblown sub-layers 14A and 14B) interposed between the first andsecond ribbon-shaped spunbond layers 12 and 16. The nonwoven fabric 10can be consolidated by mechanic embossing methods or other nonwovenfabric consolidation methods, which are illustrated in greater detailwith respect to FIG. 2 herein. As an option, the nonwoven fabric 10having a first ribbon-shaped spunbond layer 12, meltblown layer 14 (ormeltblown sub-layers 14A and 14B), and second ribbon-shaped spunbondlayer 16, contains less than about 10% by weight, or less than about 9%by weight, or less than about 8% by weight, or less than about 7% byweight, or less than about 6% by weight, or less than about 5% byweight, or less than about 4% by weight, or less than about 3% byweight, or less than about 2% by weight, or less than about 1% byweight, or 0% by weight, or from 0% to about 10% by weight, from 0% toabout 7% by weight, from 0% to about 5% by weight, or from 0% to about3% by weight, from 0% to about 2% by weight, from 0% to about 1% byweight, of total non-ribbon shaped spunbond fibers based on the totalbasis weight of the nonwoven fabric. As another option, these rangesalso can apply specifically to round-shaped spunbond fibers. As anotheroption, these restrictive amounts of the non-ribbon shaped orround-shaped spunbond fibers in particular also can apply to each therespective basis weights of the first or second ribbon-shaped spunbondlayers 12, 16 and meltblown layer 14 or to combinations of therespective basis weights of the first or second ribbon-shaped spunbondlayers 12, 16 and meltblown layer 14.

As another option, the nonwoven fabric 10 can exclude the presence ofany intervening component between the meltblown layer 14 or the stack141 of meltblown sub-layers 14A, 14B and the first or secondribbon-shaped spunbond layers 12 or 16. The intervening component mayinclude layer of non-ribbon shaped spunbond fibers, such as roundspunbond fibers or other fibers that cannot be characterized as aribbon-shaped spunbond fiber or meltblown fiber. In addition, as anotheroption, the nonwoven fabric 10 can exclude an intervening component, asdefined above, between the meltblown sub-layers 14A and 14B, if used.The exclusion of an intervening component is subject to the disclosureherein of the direct contact between the ribbon-shaped spunbond layers12 and 16 and meltblown layer 14 or meltblown sub-layers 14A and 14B, ifused.

As another option, the meltblown layer 14, or meltblown sub-layers 14Aand 14B if used, contains meltblown fibers in a total amount of at least0.1% by weight to no greater than 40% by weight of the nonwoven fabric(e.g., with reference to nonwoven fabric 10), or at least 0.5% by weightto no greater than 40% by weight of the nonwoven fabric, at least 1% byweight to no greater than 40% by weight of the nonwoven fabric, or atleast 2% by weight to no greater than 30% by weight of the nonwovenfabric, or at least 3% by weight to no greater than 25% by weight of thenonwoven fabric, or at least 4% by weight to no greater than 20% byweight of the nonwoven fabric, or at least 5% by weight to no greaterthan 15% by weight of the nonwoven fabric, or other range values withinthese ranges. As an option, the meltblown layer 14, or meltblownsub-layers 14A and 14B if used, contains meltblown fibers in a totalamount of about 10% by weight of the nonwoven fabric. The total basisweight of the nonwoven fabric 10 can be, for example, at least about 8gsm and not greater than about 40 gsm, or at least 8.5 gsm and notgreater than about 35 gsm, or at least about 9 gsm and not greater thanabout 30 gsm, or at least about 10 gsm and not greater than about 25gsm, or at least about 11 gsm and not greater than about 15 gsm, or atleast about 12 gsm and not greater than about 14 gsm, or other rangesamounts within these ranges, regardless of whether the nonwoven fabric10 includes three, four or more layers.

Manufacture of Nonwoven Fabric

With reference to FIG. 2, a schematic diagram of a forming machine 20which can be used to make an embodiment of the nonwoven fabric 10 isshown. The forming machine 20 is shown as having a beam 21 for theformation or extrusion of the first ribbon-shaped spunbond fibers 13, abeam 23 for the formation or extrusion of the meltblown fibers 15, and abeam 25 for the formation or extrusion of the second ribbon-shapedspunbond fibers 17. The forming machine 20 has an endless forming belt27 including a collection surface 22 wrapped around rollers 28 and 29 sothe endless forming belt 27 is driven in the direction as shown by thearrows.

Beam 21 can produce the first ribbon-shaped spunbond fibers 13, forexample, by use of a conventional spunbond extruder with one or morespinnerets which form ribbon-shaped spunbond fibers of polymer. Theformation of the first ribbon-shaped spunbond fibers 13 and operation ofsuch a spunbond forming beam is within the ability of those of ordinaryskill in the art in view of the descriptions herein. Suitable polymersinclude any natural or synthetic polymer that are suitable for formingspunbond fibers such as polyolefin, polyester, polyamide, polyimide,polylactic acid, polyhydroxyalkanoate, polyvinyl alcohol, polyacrylates,viscose rayon, lyocell, regenerated cellulose, or any copolymers orcombinations thereof. As an option, the polymer is a thermoplastic resinmaterial. As used herein, the term “polyolefin” includes polypropylene,polyethylene and combinations thereof. As used herein, the term“polypropylene” includes all thermoplastic polymers where at least 50%by weight of the building blocks used are propylene monomers.Polypropylene polymers also include homopolymer polypropylenes in theirisotactic, syndiotactic or atactic forms, polypropylene copolymers,polypropylene terpolymers, and other polymers comprising a combinationof propylene monomers and other monomers. As an option, polypropylenes,such as isotactic homopolymer polypropylenes made with Ziegler-Natta,single site or metallocene catalyst system, may be used as the polymer.Polypropylene, for example, may be used which has a melt flow rate (MFR)of from about 8.5 g/10min. to about 100 g/10min. or preferably from 20to 45 g/10 min., or other values. With respect to polypropylene, MFRrefers to the results achieved by testing the polymer composition by thestandard test method ASTM D1238 performed at a temperature of 230° C.and with a weight of 2.16 kg. As another option, the first ribbon-shapedspunbond fibers 13 as defined herein contain polypropylene in amounts ofat least about 50% by weight, or at least about 55% by weight, or atleast about 60% by weight, or at least about 65% by weight, or at leastabout 70% by weight or at least about 75% by weight, or at least about80% by weight, or at least about 85% by weight or at least about 90% byweight, or at least about 95% by weight, or at least about 96% byweight, or at least about 97% by weight, or at least about 98% byweight, or at least about 99% by weight, or about 100% by weight, or atleast about 50% to about 100% by weight, or at least about 60% to about100% by weight, or at least about 70% to about 100% by weight, or atleast about 80% to about 100% by weight, or at least about 90% to about100% by weight of the first ribbon-shaped spunbond fibers 13. As anotheroption, the first ribbon-shaped spunbond fibers 13 as defined herein maybe formed as homogenous solid fibers, which are distinguished frommulticomponent solid fibers (e.g., sheath-core fibers, bicomponentfibers, conjugate fibers), hollow fibers, or any combinations thereof.

In using beam 21 to produce the first ribbon-shaped spunbond fibers 13,the polymer is heated to become molten, and is extruded through theorifices in the spinneret. The extruded polymer fibers are rapidlycooled, and can be drawn by mechanical drafting rollers, fluidentrainment or other suitable means, to form the desired denier fibers.The fibers resulting from beam 21 are laid down onto the endless formingbelt 27 to create the first ribbon-shaped spunbond layer 12. Beam 21 caninclude one or more spinnerets depending upon the speed of the processor the particular polymer being used. The dimensions d1 and d2 of thefirst ribbon-shaped spunbond fibers 13 can be controlled by factorsincluding, but not limited to, spinning speed, mass throughput,temperature, spinneret geometry, blend composition, and/or drawing.

The spinnerets of beam 21 have orifices with a distinct cross-sectionthat imparts a ribbon-shaped cross-sectional geometry to the spunbondfibers. As an option, the distinct cross-section of the spinneretorifices can generally correspond in cross-sectional geometry to thatdesired in the first ribbon-shaped spunbond fibers 13 formed using thespinnerets. For example, spinnerets with rectangular-shaped orifices canbe used to form ribbon-shaped spunbond fibers having a rectangularcross-sectional geometry, a generally rectangular cross-sectionalgeometry with round edges or oval cross-sectional geometry, depending onprocessing conditions.

FIGS. 3A-3E depict several illustrative ribbon-shaped cross-sectionsthat can be used. FIG. 3A shows a rectangular cross-sectional geometry35, which has two longitudinal flat surfaces 351 and 352, and twosquared ends 353 and 354 which are longitudinally parallel to eachother; FIG. 3B shows a flat cross-sectional geometry 36; FIG. 3C shows abi-lobal cross-sectional geometry 37; FIG. 3D shows an ovalcross-sectional geometry 38; and FIG. 3E shows a ribbon-shapedcross-section 39 with at least two curvilinear surfaces. These examplesof ribbon-shaped cross-sectional geometries as defined herein are forillustration and are not exhaustive. In FIGS. 3A-3E, dimension dl, asdefined herein, is taken along a first axis and dimension d2, as definedherein, is taken along a second axis perpendicular to the first axis ofthe cross-section, wherein dimension d1 is greater than dimension d2.The aspect ratio of these cross-sectional geometries can be calculatedas the ratio: (d1/d2). The result can be reported the ratio of dimensiond1 to dimension d2 or, as a normalized value of (d1/d2):1. Further, theflat cross-sectional geometry such as illustrated in FIG. 3B, can referto geometries, for example, that have at least two opposite flat sidesand rounded sides. FIG. 3F shows a round or circular cross-sectionalgeometry 40. The dimensions d1 and d2 are equivalent in thisillustration so the aspect ratio is 1:1. As indicated, roundcross-sections have an aspect ratio less than 1.5:1 and are notribbon-shaped as defined herein. As an option, the term “ribbon-shaped”includes cross-sections having an aspect ratio of greater than 1.5:1, orabout 1.51:1 or greater, or about 1.55:1 or greater, or about 1.6:1 orgreater, or about 1.75:1 or greater, or about 2.0:1 or greater, or about2.25:1 or greater, or about 2.5:1 or greater, or about 2.75:1 orgreater, or about 3:1 or greater, or about 3.25:1 or greater, or about3.5:1 or greater, or about 3.75:1 or greater, or about 4:1 or greater,or about 4.5:1 or greater, or about 5:1 or greater, or about 5.5:1 orgreater, or about 6:1 or greater, or about 6.5:1 or greater, or greaterthan or equal to at least about 1.55:1 and less than or equal to about7:1 (i.e., from about 1.55 to about 7:1), or from about 1.6:1 to about7:1, or from about 2.5:1 to about 5.5:1, or from about 2.75:1 to 5:1, orfrom about 3:1 to about 4.5:1, or from about 3.25:1 to about 4:1, orfrom about 3.5:1 to about 3.75:1, or from about 2.5:1 to about 5:1, orfrom about 2.5:1 to about 4.5:1, or from about 2.5 to about 4:1, or fromabout 2.5 to about 3.75, or from about 2.5:1 to about 6:1, or othervalues. Methods for preparing continuous filaments having differentcross-sectional shapes or geometries which may be adapted for use inmaking ribbon-shaped filaments of the present invention are disclosed,for example, in U.S. Patent Application Publ. No. 2005/0227563 A1 (e.g.,paragraphs [0054]-[0073]), which is incorporated herein by reference.

Beam 23 produces meltblown fibers 15A. As known to those skilled in theart, a typical method of producing meltblown fibers is by the meltblownprocess that includes extruding a molten material, such as athermoplastic polymer, through a die 30 containing a plurality oforifices. The die 30 can contain from about 20 to about 100 orifices perinch of die width, or other values suitable for the meltblown layerformation. As the thermoplastic polymer, for example, exits the die 30,high pressure fluid, usually air, attenuates and spreads the polymerstream to form the meltblown fibers 15A. The meltblown process allowsthe use of various different polymers. Non-limiting examples includepolypropylene (e.g., MFR of at least about 400 g/10min. to no greaterthan about 2000 g/10min.), blends including polypropylene (e.g. MFR ofat least about 7.5 g/10min. to no greater than about 2000 g/10min.),polyethylene (e.g., melt flow index (MFI) of at least about 20 g/10min.to no greater than about 250 g/10 min.), polyester (e.g., intrinsicviscosity of at least about 0.53 dL/g to no greater than about 0.64dL/g), polyamide, polyurethane, polyphenylene sulphide, or other fibermaterials, such as those indicated for use in forming the firstribbon-shaped spunbond fibers 13. With respect to polypropylene, MFR isa measure of polymer viscosity performed as per standard test methodASTM D1238 using a temperature of 230° C. and a weight of 2.16 kg. Withrespect to polyethylene, MFI is a measure of polymer viscosity performedas per standard test method ASTM D1238 using a temperature of 190° C.and a weight of 2.16 kg. Any of the foregoing polypropylene polymers mayinclude vis-breaking additives (e.g. peroxide additives or non-peroxidecontaining additives, which are available, for example, under thetradename Irgatec® CR 76, from BASF Corporation of Ludwigshafen,Germany. The polymers and blends used during meltblown productionordinarily have a low viscosity or are designed and processed in a wayto have their viscosity reduced during their extrusion one of thevariables used to decrease their in situ viscosity is the use of arelatively high melt temperature (compared to other productionprocesses). The melt temperature can be adjusted during production bymeans of electrical heating systems in the extrusion section or othermeans known in the industry. The meltblown fibers 15 resulting from beam23 are laid down onto first ribbon-shaped spunbond layer 12, carried bythe endless forming belt 27, to create the meltblown layer 14. Theconstruction and operation of beam 23 for forming the meltblown fibers15 and the meltblown layer 14 can be adapted based on conventionalequipment in view of the present disclosures. For example, U.S. Pat. No.3,849,241 (e.g., column 7, line 14 to col. 12, line 29), which isincorporated herein by reference, shows such conventional arrangementswhich may be adapted. Other methods for forming the meltblown layer 14are contemplated for use with the present invention.

Beam 25 produces the second ribbon-shaped spunbond fibers 17, such as byuse of a conventional spunbond extruder, and can have a substantiallysimilar design as beam 21. Beam 25 can involve different processingparameters than those of beam 21 as long as ribbon-shaped spunbondfibers are formed. For example, the polymer used in beam 25 can besimilar or different from the polymers used in beam 21. The temperatureand attenuation for beam 25 can also differ from beam 21. The spinneretsof beam 25 have orifices with a distinct cross-section that impart aribbon-shaped cross-sectional geometry to the resulting ribbon-shapedspunbond fibers 17. The spinnerets of beam 25 yield ribbon-shapedspunbond fibers 17 with a cross-sectional geometry and/or aspect ratiowhich is the same or different from the ribbon-shaped cross-sectionalgeometry and aspect ratio of first ribbon-shaped spunbond fibers 13. Thesecond ribbon-shaped spunbond fibers 17 of the second ribbon-shapedspunbond layer 16 can comprise, for example, ribbon-shaped fibers havinga cross-sectional geometry such as illustrated in FIGS. 3A-3E. Thesecond ribbon-shaped spunbond fibers 17 resulting from beam 25 are laiddown onto the meltblown layer 14, which is on the first ribbon-shapedspunbond layer 12 that is carried on the endless forming belt 27, tocreate the second ribbon-shaped spunbond layer 16.

In another option, the forming machine 20 can include a beam 31 locatedalong endless forming belt 27 between beam 23 and beam 25. Beam 31 canbe configured to produce a second meltblown layer on meltblown layer 14or a second meltblown sub-layer 14B, before the formation of the secondribbon-shaped spunbond layer 16 thereon at beam 25. This arrangement, ifused, can form two consecutive meltblown layers, such as meltblownsub-layers 14A and 14B as illustrated in FIG. 1. Beam 31, if included,can have similar or dissimilar settings, and operabilities as beam 23and may use the same or different polymers as used in beam 23.Additional beams can be added to form additional meltblown layers orsub-layers or additional ribbon-shaped spunbond layers, consistent withthe nonwoven fabric 10 described herein.

The resulting nonwoven fabric 10 can be fed through bonding rolls 32 and33 to consolidate the nonwoven fabric 10. As an option, the nonwovenfabric 10 can be embossed with a pattern from at least one side. FIG. 5illustrates the nonwoven fabric 10 after being embossed with a patternon both sides. The surfaces of one or both of the bonding rolls 32 and33 can be provided, for example, with a raised pattern such as spots orgrids. As an option, one bonding roll 32 or 33 can include a raisedpattern while the other bonding roll (32 or 33) can be smooth. Thebonding rolls 32 and 33 can be heated to the softening temperature ofthe polymer used to form the layers of the nonwoven fabric 10. As thenonwoven fabric 10 passes between the heated bonding rolls 32 and 33,the material is embossed by the bonding rolls in accordance with thepattern on the rolls to create a pattern of discrete bonded areas. Thebonded areas are bonded from layer to layer with respect to theparticular filaments and/or fibers within each layer. FIG. 4 shows anillustration of a nonwoven fabric 10 with a pattern 18 of such discretethermally bonded areas 19. The total area of the bond pattern 18relative to the overall surface area of the fabric can be, for example,from about 10% to about 25%, or from about 13% to about 25%, or fromabout 15% to about 25%, or from about 18% to about 25%, or from about15% to about 23%, or from about 16% to about 23%, or other values. Theembossed pattern shape of the discrete thermally bonded areas 19 can be,for example, diamond, oval, or other discrete shapes. FIG. 5 shows aview of one of the indicated discrete thermally bonded areas 19 throughthe cross-section of the nonwoven fabric 10. The bonding rolls 32 and 33can have embossing protuberances that are synchronized to compress thenonwoven fabric 10 from opposite sides at corresponding locations (asshown) or different locations on each side of the nonwoven fabric 10.The depth of compression produced from the opposite sides of thenonwoven fabric 10 by the embossing protuberances of the respectivebonding rolls 32 and 33 can have different (as shown) or the same. Suchbonding, which is sometimes referred to as discrete area or spotbonding, is well-known in the art and can be carried out as described bymeans of heated rolls or by means of ultrasonic heating of the nonwovenfabric 10 to produce fibers and layers having discrete thermally bondedfibers. Thermal pattern bonding such as described, for example, in Brocket al., U.S. Pat. No. 4,041,203 (e.g., col. 6, lines 10-28), which isincorporated herein by reference, can be adapted to provide theindicated discrete or spot bonding. In FIG. 5, the fibers of themeltblown layer 14 in the fabric laminate 10 can fuse within the bondareas while the ribbon-shaped fibers 13 and 17 of the first and secondribbon-shaped spunbond layers 12 and 16, respectively, retain some oftheir integrity, in order to achieve good strength characteristics. Forheavier basis weight nonwoven fabrics, for example, sonic bondingmethods and devices which are generally known can be adapted for use.Other nonwoven fabric bonding methods known in the art also can beadapted and used. Furthermore, it is envisioned that the nonwoven fabricmay be created from discrete spunbond or meltblown layers that areformed, rolled, and later joined or laminated by methods well known inthe art (including stacking the discrete layers without bonding) ratherthan the discrete spunbond and/or meltblown layers being laid by asingle forming machine as presented above.

As an option, the forming machine 20 can be provided as a modularstructure of the spunbond and meltblown components. A common operatingconsole for all the spinning stations can be provided with the commonhigh speed belt for all spinning stations. A high speed winding system(not shown) can be provided as an option with a downstream slitter andrewinder downstream of the embossing station.

In further reference to FIG. 2, distance 34 is the distance from the dieof beam 23 to the collection surface 22 of the endless forming belt 27.As indicated, nonwoven fabrics made from the first and secondribbon-shaped spunbond layers 12 and 16 as outer layers with aninterposed meltblown layer 14 as described can have a significantlylower Flow Ratio than equivalent examples made from round-shapedspunbond fibers or round-shaped spunbond layers. It also has beenobserved that the difference in the Flow Ratio can be more pronouncedfor examples where the meltblown fibers 15A were applied to theribbon-shaped spunbond layer 12 and meltblown fibers 15B were applied tothe underlying meltblown fibers 15A and ribbon-shaped spunbond layer 12from a smaller distance from die to collector (or “DCD”) from beam 23,beam 31 or other beams. For example, in examples with an S/M/S orS/M/M/S layered construction, having a total basis weight of at leastabout 13 to no greater than about 14 gsm, which includes about meltblownfibers in an amount of at least about 1.3 gsm to no greater than about1.5 gsm, the DCD can have a significant impact on the above mentionedFlow Ratio. That relationship between the change in ratio and the DCDindicates that the synergy between the meltblown fibers 15A and 15B andribbon-shaped spunbond fibers 13, 17 can be even more pronounced whenthe meltblown fibers 15A and 15B are projected with more force due tohaving to travel a shorter distance toward the underlying ribbon-shapedspunbond layer 12. The meltblown fibers 15A and 15B may have the abilityto form a more two-dimensional and rigid web when applied to anunderlying ribbon-shaped spunbond layer 12 rather than an underlyinground-shaped spunbond layer. This is supported by gathered pore sizedata, such as disclosed in the examples section herein. The dataindicates that the synergy exists specifically for examples where thereare fewer large pores or, in other words, there is a lower fraction oflarge pores in the pore distribution.

Uses of Nonwoven Fabrics

The nonwoven fabrics of the present invention can be used as a barrierfabric or other component within a multitude of personal hygieneproducts. These personal hygiene products can include, for example,diapers. Diapers can include various diaper components, such asdescribed in U.S. Patent Application Publ. No. 2005/0215155 A1 (e.g.,paragraphs [0047]-[0069]), which is incorporated herein by reference.The nonwoven fabrics of the present invention can be used in place ofthe nonwoven fabrics described in the diapers or diaper components ofthe above incorporated published patent application, such as, forexample, the nonwoven fabrics that form the topsheet, backsheet or legcuffs. The nonwoven fabrics of the present invention can also be used asa core wrap in diapers or diaper components. Furthermore, the nonwovenfabric of the present invention can be used in place of other substrateswherein the breathability and/or barrier protection characteristics ofthe nonwoven fabric of the present invention are desired. As an option,the nonwoven fabric of the present invention can be used as a diaper oradult incontinence product leg cuff. As another option, the nonwovenfabrics of the present invention can be used as a barrier layer withinabsorbent personal hygiene products. The nonwoven fabric can be used asa barrier layer, such as a backsheet, topsheet, anal cuff, outer cover,and barrier cover. Furthermore, the nonwoven fabric of the presentinvention can be used in disposable personal hygiene products including,but not limited to, drapes (e.g., surgical and other medical drapes),gowns (e.g., surgical and other medical gowns), sterilization wraps, andfoot covers.

The present invention will be further clarified by the followingexamples, which are intended to be only exemplary of the presentinvention.

EXAMPLES Test Methods

Basis Weight

Basis weight of the following examples was measured in a way that isconsistent with ASTM D756 and EDANA ERT-40,3-90 test method. The resultswere provided in units of mass per unit area in g/m² (gsm) and wereobtained by weighing a minimum of ten 10 cm by 10 cm samples of each ofthe Comparative Examples and Examples below.

Air Permeability

Air permeability data were produced using a TexTest FX3300 AirPermeability Tester manufactured by TexTest AG of Zurich, Switzerland.The TexTest FX3300 Air Permeability Tester was used accordingly with themanufacturer's instructions using a 38 mm orifice and a pressure drop of125 Pa as per test method ASTM D-737 test method. Readings were made onsingle ply or layer samples and double ply or layer samples of theComparative Examples and Examples below and, the results were recordedin the units of m³/m²/min.

Low Surface Tension Strike Through (LSTST)

The Low Surface Tension Strike Through method utilized was based onEDANA test method WSP70.3(05) with a few modifications. A firstmodification to EDANA test method WSP70.3(05) was that a low surfacetension fluid, described below in more detail, was utilized instead ofsimulated urine solution of a 9 g/1 solution of sodium chloride indistilled water having a surface tension of 70±2 mN/m. A secondmodification to EDANA test method WSP70.3(05) was that for the samplesof the Comparative Examples and Examples where the strike through timewas less than 8 seconds when performed on a single ply, the measurementwas performed on two plies or layers of the sample. The secondmodification was needed to increase the time needed to absorb the 5 mlof fluid and subsequently reduce the variability of the Low SurfaceTension Strike Through method. A third modification to EDANA test methodWSP70.3(05) was that the Ahlstrom Filtration filter paper code #989(available from Empirical Manufacturing, Inc., 7616 Reinhold Drive,Cincinnati, Ohio 45237, USA) having dimensions of 4 inches by 4 incheswas used as a blotter or absorbent paper positioned under the sample,instead of the suggested blotter paper ERT FF2, which is available fromHollingsworth & Vose Co. or East Walpole, Mass. The five blotter papersused per test were stacked with the rougher surface facing the incomingfluid.

The low surface tension liquid utilized in the EDANA test methodWSP70.3(05) was prepared as follows: in a clear clean flask, 500 mldistilled water was provided and 2.100 grams of an nonionic surfactant,which is available under the trademark Triton® X-100 from Sigma-Aldrichof St. Louis, Mo., was added to the flask containing the 500 mldistilled water. Thereafter, distilled water in an amount of 5,000 mlwas added to the same flask. The distilled water and nonionic surfactantsolution was mixed for a minimum of 30 minutes. The surface tension ofthe solution was measured, to ensure it was between 31 mN/m and 32.5mN/m, and preferably about 32mN/m, to qualify as a low surface tensionliquid. The surface tension of the solution was determined by methodD1331-56 (“Standard test method for surface and interfacial tensionsolution of surface active agents”) using a Krüss K11 MK1 tensiometer.

For the purposes herein, the LSTST-Time is defmed as the strike throughtime in seconds measured by this method. The LSTST-Flow is defmed asfollow:

LSTST-Flow = 5(ml)/LSTST-Time(seconds).

The units for LSTST-Flow are ml/sec. It is an expression of the averageflow rate of the low surface tension fluid through the sample during theduration of the test.

Flow Ratio

Flow Ratio is defmed as the ratio of LSTST-Flow to air permeability.This comparison was performed by measuring the LSTST-Flow and airpermeability of each of the Comparative Examples and Examples below. Themeasurements were taken of each example while ensuring the samples usedfor the measurements had the same number of plies for both theLSTST-Flow and air permeability measurements.

Flow  Ratio = FR = LSTST-Flow/Air  permeability.

For the Flow Ratio, the units for LSTST-Flow are ml/sec, and the unitsfor air permeability are m³/m²/min.

Fiber Dimension and Aspect Ratio

Fiber Dimension Test Method 1 is utilized to measure the dimensions d1and d2 of round fibers in the samples of the Comparative Examples andExamples below. Fiber Dimension Test Method 1 assumes that round fiberhave dimensions d1 and d2 that are equal. As will be discussed below,Fiber Dimension Test Method 1 was also used to measure the dimension d1or the fiber width of the ribbon-shaped spunbond fibers of Examples 7-12and 15-16 for comparison purposes. Fiber Dimension Test Method 1 wasmeasured using a microscope positioned to view the fabric at 90° fromthe fabric surface. For spunbond fibers specifically, an opticalmicroscope was used to magnify the side-view of the selected fibers inorder to measure dimension d1 of the fibers. The optical microscope wasfirst calibrated using an acceptable standard (e.g. Optical gridcalibration slide 03A00429 S16 Stage Mic 1MM/0.01 DIV available fromPyser-SGI Limited of Kent, UK or SEM Target grid SEM NIST SRM 4846#59-27F). For each layer, Fiber Dimension Test Method 1 utilized thecommon practice of selecting fibers at random to measure the dimensiond1 of fibers. In each layer of the sample taken from the ComparativeExamples and Examples, fibers were selected by drawing a line betweentwo points of the sample being examined and selecting a minimum of 10fibers for measurement. Such an approach minimizes multiple measurementsof the same fiber. After magnification, the dimensions d1 were measuredof the selected fibers along the same axis as the line drawn between twopoints of the sample. The average of the measured dimensions d1 of thefibers was calculated based on the count of the fibers. As stated above,because the dimensions d1 and d2 are assumed equal for round-shapedfibers, the aspect ratio for such fibers was about 1:1.

Accordingly, the dimension d1 of the meltblown fibers were also measuredas per Fiber Dimension Test Method 1 with the exception that a scanningelectron microscope was used to achieve a greater degree ofmagnification. It is generally accepted that meltblown fibers have around cross-sectional geometry, therefore it was assumed that meltblownfiber cross-sections will have dimensions d1 and d2 that are equal,producing an aspect ratio of 1:1.

For ribbon-shaped spunbond fibers, Fiber Dimension Test Method 1 is nota suitable method to measure the dimensions d1 and d2 needed for thecomputation of the aspect ratio. This is because Fiber Dimension TestMethod 1 does not provide information about dimension d2 and, alsobecause the average fiber dimension of the ribbon-shaped spunbond fibersthat was observed and measured by Fiber Dimension Test Method 1 istypically less than the actual average of dimension dl, as definedherein. The discrepancy between the average fiber dimension observed andmeasured by Fiber Dimension Test Method 1 and actual average ofdimension d1 is because not all of the ribbon-shaped spunbond fibersobserved are lying flat in the X-Y plane of the ribbon-shaped spunbondlayer, with their respective longest cross-sectional dimension allpositioned along the X-Y plane or all positioned along the Z plane thatis perpendicular to the X-Y plane. Therefore, Fiber Dimension TestMethod 2 was used to measure the dimensions d1 and d2 and determine theaspect ratios of ribbon-shaped spunbond fibers, consistent with thedefinition of aspect ratio. For Fiber Dimension Test Method 2, a samplewas taken from the Examples below and the ribbon-shaped spunbond fibersin the sample were cut perpendicular to their length. After cutting theribbon-shaped spunbond fibers, their cross-sections were observed usingan optical microscope that had been calibrated in a similar manner as inFiber Dimension Test Method 1. The dimensions d1 and d2 were measuredfor a minimum of 8 representative ribbon-shaped spunbond fibers selectedfrom the sample and average of the measurements of dimensions d1 and d2,respectively, was calculated based on number of fibers. The FiberDimension Test Method 2 is also a suitable method to measure dimensiond1 and d2 and compute the aspect ratio for round-shaped fibers.

Pore Size Distribution

The pore size distributions of the Comparative Examples and Exampleswere measured using a capillary flow porometer. The instrument used wasa PMI Capillary Flow Porometer model CFP-1200-ACL-E-X-DR-2S, availablefrom Porous Materials, Inc. of Ithaca, N.Y. The instrument utilized awetting fluid having a surface tension of 15.9 mN/m, available under thetrademark Galwick® from Porous Materials, Inc.

The method used to measure the cumulative flow and pore sizedistribution was provided by the equipment manufacturer and isidentified as “Capillary Flow Porometry Test” using the “Wet up/Dry up”mode. A wrinkle free, clean circular sample is obtained from theComparative Examples and Examples having a diameter of about 1.0 cm. Thesample was saturated with the wetting fluid and then mounted into thecell of the PMI Capillary Flow Porometer, as per the manufacturer'sinstruction. When the mounting was complete, the apparatus was run bythe apparatus software in the “Wet up/Dry up” mode to first record aflow vs. pressure curve for the sample saturated with the wetting fluid.When the flow v. pressure curve is recorded for the saturated sample,and the fluid has been expulsed from the pores, a flow vs. pressurecurve was measured a second time on the same sample mounted in theinstrument. The data generated includes the mean flow pore or “MFP,”where the pore size was calculated from the pressure where the half-drycurve intersects with the wet curve. The mean flow pore diameter wassuch that 50% of the flow is through pores larger than the mean flowpore. The measurement of pore size at 10% cumulative filter flow and thepore size at 25% cumulative filter flow were used as a way tocharacterize the presence of large pores.

EXAMPLES AND RESULTS

Comparative Examples and Examples 1 to 16 included nonwoven fabrics thatwere prepared on a line fitted with four production beams (e.g., first,second, third and fourth production beams, respectively) designed byReifenhauser Reicofil GmbH & Co. KG of Troisdorf, Germany. The firstproduction beam formed spunbond fibers that were deposited on a movingbelt to form a first spunbond layer. The second production beam formedmeltblown fibers that were laid on top of the first spunbond layer toform a first meltblown sub-layer. The third production beam formedmeltblown fibers that were laid on top of the first meltblown sub-layerto form a second meltblown sub-layer. The distance from die to collector(DCD) for the second and third meltblown production beams were adjustedbetween the various samples as indicated herein. The fourth productionbeam formed spunbond fibers that were laid on top of the secondmeltblown sub-layer to form a second spunbond layer. The resulting stackof layers was bonded together using a calender fitted with a smooth rolland an embossed roll. The embossed roll was provided with two differentpatterns that were positioned side by side to provide ComparativeExamples and Examples with specific bonding patterns as indicated below.One of the patterns is identified in the data below as pattern A andincludes an angled oval pattern embossed with pattern available underthe commercial code U2888 from A+E Ungricht GMBH & Co. KG ofMonchengladbach, Germany. Pattern A is described as being formed from aplurality of raised pins with a surface contact area or “land” areacovering at least about 16% and no greater than about 20% of the totalarea of the embossed portion of the roll containing pattern A and havinga pin density of about 50 pins/cm². The second pattern on the embossedroll is identified in the data below as pattern B, which is availableunder the commercial code U5444 through equipment manufacturerReifenhauser Reicofil GmbH & Co. KG of Troisdorf, Germany and isproduced by A+E Ungricht GMBH & Co. Kg of Monchengladbach, Germany.Pattern B included an angled oval pattern having a plurality of raisedpins with a surface contact area or “land” area covering more than 18%and no greater than 25% of the total area of the embossed portion of theroll containing pattern B and having a pin density of about 62.4pins/cm². The resulting fabrics obtained from pattern A and pattern Bincluded an S/M/M/S layered construction.

For the production of the Comparative Examples and Examples 1 to 16, thefirst and fourth beams were fitted with the spinnerets including eithercapillaries with a round cross-sectional geometry to produceround-shaped spunbond fibers or capillaries with ribbon-shapedcross-sectional geometry that produced the ribbon-shaped spunbondfibers. The capillaries with the round cross-sectional geometry haddimension d1 and d2 of 0.6 mm and an aspect ratio of about 1.0:1.0. Thecapillaries with the ribbon-shaped cross-sectional geometry had arectangular shape with rounded corners, a dimension d1 of about 1.5 mmand dimension d2 of about 0.24 mm producing an aspect ratio of about6.25:1. The throughput was maintained on average at about 0.4 gram percapillary or hole and per minutes (ghm)

In each of Comparative Examples and Examples 1 to 16, the spunbondfibers formed by the first production beam and the fourth productionbeam were extruded from a polypropylene resin having a melt flow rate(“MFR”) of 36 g/10 min., available under the tradename PP3155 fromExxonMobil Chemicals, Inc. of Houston, Tex. For Comparative Examples andExamples 1 to 16, the molten polymer temperature was recorded at about242° C. for first production beam and about 245° C. for fourthproduction beam. In each of Comparative Examples and Examples 1 to 16,the meltblown fibers formed by the second and third production beamswere extruded from a polypropylene resin having a MFR of 1500 g/10 min.In each of Comparative Examples and Examples 1 to 16, the meltblownlayer, which included meltblown fibers formed by the second and thirdproduction beams, had basis weight of about 10% of the total basisweight.

Examples 7-12 and 15-16 included two spunbond layers formed fromribbon-shaped spunbond fibers. Accordingly, select representativesamples were taken from Examples 7-12 and the dimensions d1 and d2 forthe ribbon-shaped spunbond fibers in each representative sample weremeasured according to Fiber Dimension Test Method 2. Based on thismethod, it was found that Examples 7-12 had an average dimension d1 ofabout 27.0 microns and an average cross-sectional dimension d2 of about8.3 microns. From these average dimensions d1 and d2 an aspect ratio ofabout 3.25:1 was calculated for the ribbon-shaped spunbond fibers ofExamples 7-12. For each of Examples 15 and 16, the ribbon-shapedspunbond fibers were formed using the same process conditions.Accordingly, select representative samples were taken from Examples 15and 16 and the dimensions d1 and d2 for the ribbon-shaped spunbondfibers in each sample were measured according to Fiber Dimension TestMethod 2. The average dimension d1 was 26.1 microns and the averagedimension d2 was 8.4 microns. From the average d1 and d2 an aspect ratioof about 3.15:1 was calculated for the ribbon-shaped spunbond fibers ofExamples 15 and 16 Comparative Examples 1-6 and 13-14 included twospunbond layers formed from round-shaped spunbond fibers. For thoseround-shaped spunbond fibers, the averages of dimensions d1 weremeasured according to Fiber Dimension Test Method 1.

Comparative Example 1

Comparative Example 1 was produced on the above described productionbeams wherein the first and fourth production beans had spinnerets withcapillaries having a round cross-sectional geometry, as indicated above.The resulting S/M/M/S layers were then bonded using the embossed rollerwith pattern A. The resulting fabric included a first round-shapedspunbond layer, two meltblown layers and a second round-shaped spunbondlayer, wherein the spunbond layers have fibers with a roundcross-sectional geometry and an aspect ratio of less than 1.5. Themeltblown layers of Comparative Example 1 were formed from the secondand third production beams, which were positioned such that the DCD was110 mm. The process conditions for forming Comparative Example 1 wereselected to approximate the commercial production of S/M/M/S suitablefor use as barrier leg cuff fabric. The average basis weight for eachlayer was calculated based on the measured total basis weight for thefabric and the throughput recorded for each production beam The totalbasis weight measurement, the basis weight calculations for each layerand average fiber dimension measurements, according to Fiber DimensionTest Method 1, for Comparative Example 1 are reproduced below in Table1:

TABLE 1 Basis Weight Measurement and Calculations Per Layer and AverageFiber Dimension Measurements for Comparative Examples 1 & 2. BasisWeight Round-shaped spunbond fibers from 1^(st) 5.94 gsm production beamMeltblown fibers from 2^(nd) production beam 0.66 gsm Meltblown fibersfrom 3^(rd) production beam 0.66 gsm Round-shaped spunbond fibers from4^(th) 5.94 gsm production beam Total basis weight measured 13.2 gsmAverage Fiber Dimension Measurements According To Fiber Dimension TestMethod 1 Round-shaped spunbond fibers from 1^(st) 14.0 μm productionbeam Meltblown fibers from 2^(nd) production beam  1.1 μm Meltblownfibers from 3^(rd) production beam  1.2 μm Round-shaped spunbond fibersfrom 4^(th) 14.5 μm production beam

Comparative Example 2

Comparative Example 2 was produced in the same manner as ComparativeExample 1 with the exception that the bonding pattern B was used.Comparative Example 2 had the same total basis weight measurement, basisweight calculations per layer and average fiber dimension measurementsas Comparative Example 1, which are provided above in Table 1.

Comparative Example 3

Comparative Example 3 was produced in the same manner as ComparativeExample 1 with the exception that the DCD was 150 mm. The total basisweight measurement, basis weight calculations per layer and averagefiber dimension measurements, according to Fiber Dimension Test Method1, for Comparative Example 3 are reproduced below in Table 2:

TABLE 2 Basis Weight Measurement and Calculations Per Layer and AverageFiber Dimension Measurements for Comparative Examples 3 & 4 Basis WeightRound-shaped spunbond fibers from 1^(st)  5.9 gsm production beamMeltblown fibers from 2^(nd) production beam 0.66 gsm Meltblown fibersfrom 3^(rd) production beam 0.66 gsm Round-shaped spunbond fibers from4^(th)  5.9 gsm production beam Total basis weight measured 13.1 gsmAverage Fiber Dimension Measurements According To Fiber Dimension TestMethod 1 Round-shaped spunbond fibers from 1^(st) 14.5 μm productionbeam Meltblown fibers from 2^(nd) production beam  1.1 μm Meltblownfibers from 3^(rd) production beam  1.2 μm Round-shaped spunbond fibersfrom 4^(th) 14.0 μm production beam

Comparative Example 4

Comparative Example 4 was produced in the same manner as ComparativeExample 2 with the exception that the DCD was 150 mm. ComparativeExample 4 had the same total basis weight measurement, basis weightcalculations per layer and average fiber dimension measurements asComparative Example 3, which are provided above in Table 2.

Comparative Example 5

Comparative Example 5 was produced in the same manner as ComparativeExample 1 with the exception that the DCD was 190 mm. The total basisweight measurement, basis weight calculations per layer and averagefiber dimension measurements, according to Fiber Dimension Test Method1, for Comparative Example 5 are reproduced below in Table 3:

TABLE 3 Basis Weight Measurement and Calculations Per Layer and AverageFiber Dimension Measurements for Comparative Examples 5 & 6 Basis WeightRound-shaped spunbond fibers from 1^(st) 5.85 gsm production beamMeltblown fibers from 2^(nd) production beam 0.65 gsm Meltblown fibersfrom 3^(rd) production beam 0.65 gsm Round-shaped spunbond fibers from4^(th) 5.85 gsm production beam Total basis weight measured 13.0 gsmAverage Fiber Dimension Measurements According To Fiber Dimension TestMethod 1 Round-shaped spunbond fibers from 1^(st) 13.5 μm productionbeam Meltblown fibers from 2^(nd) production beam  1.2 μm Meltblownfibers from 3^(rd) production beam  1.2 μm Round-shaped spunbond fibersfrom 4^(th) 14.5 μm production beam

Comparative Example 6

Comparative Example 6 was produced in the same manner as ComparativeExample 2 with the exception that the DCD was 190 mm. ComparativeExample 6 had the same total basis weight measurement, basis weightcalculations per layer and average fiber dimension measurements asComparative Example 5, which are provided above in Table 3.

Example 7

Example 7 was produced using the same production beams as ComparativeExample 1, except the first and fourth production beams includedspinnerets included capillaries having a ribbon-shaped geometry, asindicated above. As a result, Example 7 included two spunbond layers ofribbon-shaped spunbond fibers instead of round-shaped spunbond fibers.While the polymer throughputs for the first and fourth production beamswere kept about the same as those used for Comparative Example 1, someof the other fiber spinning conditions (e.g. volume of cooling air) hadto be adjusted to achieve process stability. The total basis weightmeasurement, basis weight calculations per layer and average fiberdimension measurements, according to Fiber Dimension Test Method 1, forExample 7 are reproduced below in Table 4:

TABLE 4 Basis Weight Measurement and Calculations Per Layer and AverageFiber Dimension Measurements for Examples 7 & 8 Basis WeightRound-shaped spunbond fibers from 1^(st) 6.075 gsm production beamMeltblown fibers from 2^(nd) production beam 0.675 gsm Meltblown fibersfrom 3^(rd) production beam 0.675 gsm Round-shaped spunbond fibers from4^(th) 6.075 gsm production beam Total basis weight measured 13.5 gsmAverage Fiber Dimension Measurements According To Fiber Dimension TestMethod 1 Ribbon-shaped spunbond fibers from 1^(st) 19.5 μm productionbeam Meltblown fibers from 2^(nd) production beam 1.1 μm Meltblownfibers from 3^(rd) production beam 1.2 μm Ribbon-shaped spunbond fibersfrom 4^(th) 21.0 μm production beam

Example 8

Example 8 was produced in the same manner as Example 7 with theexception that the bonding pattern B was used. The total basis weightcalculation for Example 8 was the same total basis weight as Example 7.In addition, the individual S/M/M/S layers of Example 8 had the samebasis weight calculations as Example 7, shown in Table 4. The averagefiber dimension of the fibers made from beams 1, 2, 3, and 4 in Example8 were measured using Fiber Dimension Test Method 1 and were the same asExample 7, shown above in Table 4.

Example 9

Example 9 was produced in the same manner as Example 7 with theexception that the DCD was set at 150 mm. The total basis weightmeasurement, basis weight calculations per layer and average fiberdimension measurements, according to Fiber Dimension Test Method 1, forExample 9 are reproduced below in Table 5:

TABLE 5 Basis Weight Measurement and Calculations per Layer and AverageFiber Dimension Measurements for Examples 9 & 10 Basis WeightRound-shaped spunbond fibers from 1^(st) 6.21 gsm production beamMeltblown fibers from 2^(nd) production beam 0.69 gsm Meltblown fibersfrom 3^(rd) production beam 0.69 gsm Round-shaped spunbond fibers from4^(th) 6.21 gsm production beam Total basis weight measured 13.8 gsmAverage Fiber Dimension Measurements According to Fiber Dimension TestMethod 1 Ribbon-shaped spunbond fibers from 1^(st) 20.5 μm productionbeam Meltblown fibers from 2^(nd) production beam  1.1 μm Meltblownfibers from 3^(rd) production beam  1.2 μm Ribbon-shaped spunbond fibersfrom 4^(th) 22.5 μm production beam

Example 10

Example 10 was produced in the same manner as Example 8 with theexception that the DCD was set at 150 mm. The total basis weightcalculation for Example 10 were the same total basis weight as Example9. In addition, the individual S/M/M/S layers of Example 10 had the samebasis weight calculations as Example 9, shown in Table 5. The averagefiber dimension of the fibers made from beams 1, 2, 3, and 4 in Example10 were measured using Fiber Dimension Test Method 1 and were the sameas Example 9, shown above in Table 5.

Example 11

Example 11 was produced in the same manner as Example 7 with theexception that the DCD was set at 190 mm. The total basis weightmeasurement, basis weight calculations per layer and average fiberdimension measurements, according to Fiber Dimension Test Method 1, forExample 11 are reproduced below in Table 6:

TABLE 6 Basis Weight Measurement and Calculations per Layer and AverageFiber Dimension Measurements for Examples 11 & 12 Basis WeightRound-shaped spunbond fibers from 1^(st) 5.805 gsm production beamMeltblown fibers from 2^(nd) production beam 0.645 gsm Meltblown fibersfrom 3^(rd) production beam 0.645 gsm Round-shaped spunbond fibers from4^(th) 5.805 gsm production beam Total basis weight measured  12.9 gsmAverage Fiber Dimension Measurements According To Fiber Dimension TestMethod 1 Ribbon-shaped spunbond fibers from 1^(st) 19.5 μm productionbeam Meltblown fibers from 2^(nd) production beam  1.1 μm Meltblownfibers from 3^(rd) production beam  1.2 μm Ribbon-shaped spunbond fibersfrom 4^(th) 21.0 μm production beam

Example 12

Example 12 was produced in the same manner as Example 8 with theexception that the DCD was set at 190 mm. The total basis weightcalculation for Example 12 was the same total basis weight as Example11. In addition, the individual S/M/M/S layers of Example 12 had thesame basis weight calculations as Example 11, shown in Table 6. Theaverage fiber dimension of the fibers made from beams 1, 2, 3, and 4 inExample 12 were measured using Fiber Dimension Test Method 1 and werethe same as Example 11, shown above in Table 6.

Comparative Example 13

Comparative Example 13 was made using the production beams describedabove with reference to Comparative Examples 1-6. The resulting fabricincluded a first round-shaped spunbond layer, two meltblown layers and asecond round-shaped spunbond layer having fibers with a roundcross-sectional geometry and an aspect ratio of less than 1.5:1. Howeverprocess conditions including polymer throughputs were modified toproduce an S/M/M/S fabric that is more typical of those used for medicalprotective barrier applications, such as gown and drapes. The basisweight measurement, basis weight calculations per layer and averagefiber dimension measurements, according to Fiber Dimension Test Method1, for Comparative Example 13 are reproduced below in Table 7:

TABLE 7 Basis Weight Measurement and Calculations per Layer and AverageFiber Dimension Measurements for Comparative Examples 13 & 14 BasisWeight Round-shaped spunbond fibers from 1^(st) 18.1 gsm production beamMeltblown fibers from 2^(nd) production beam  4.4 gsm Meltblown fibersfrom 3^(rd) production beam  4.4 gsm Round-shaped spunbond fibers from4^(th) 18.1 gsm production beam Total basis weight measured 45.5 gsmAverage Fiber Dimension Measurements According To Fiber Dimension TestMethod 1 Round-shaped spunbond fibers from 1^(st) 14.0 μm productionbeam Meltblown fibers from 2^(nd) production beam  1.5 μm Meltblownfibers from 3^(rd) production beam  1.4 μm Round-shaped spunbond fibersfrom 4^(th) 14.5 μm production beam

Comparative Example 14

Comparative Example 14 was produced in the same manner as ComparativeExample 13, except that bonding pattern B was utilized. ComparativeExample 14 had the same total basis weight, basis weight calculationsper layer and average fiber dimension measurements as ComparativeExample 13, which are provided above in Table 7.

Example 15

Example 15 was made in the same manner and using the same productionbeams as Comparative Example 13, except that the first and fourthproduction beams included spinnerets having capillaries with aribbon-shaped geometry, as indicated. Example 15 included tworibbon-shaped spunbond layers formed from ribbons-shaped spunbondfibers. The total basis weight for Example 15 was the same total basisweight calculation as Comparative Example 13. In addition, theindividual S/M/M/S layers of Example 15 had the same basis weightcalculations as Comparative Example 13, shown in Table 7. The averagefiber dimension measurements, according to Fiber Dimension Test Method 1for Example 15 are reproduced below in Table 8:

TABLE 8 Basis Weight Measurement and Calculations per Layer AverageFiber Dimension Measurements for Examples 15 & 16 Basis WeightRibbon-shaped spunbond fibers from 1^(st) 18.25 gsm production beamMeltblown fibers from 2^(nd) production beam  4.5 gsm Meltblown fibersfrom 3^(rd) production beam  4.5 gsm Ribbon-shaped spunbond fibers from4^(th) 18.25 gsm production beam Total basis weight measured  45.5 gsmAverage Fiber Dimension Measurements According To Fiber Dimension TestMethod 1 Ribbon-shaped spunbond fibers from 1^(st) 22.5 μm productionbeam Meltblown fibers from 2^(nd) production  1.5 μm beam Meltblownfibers from 3^(rd) production  1.3 μm beam Ribbon-shaped spunbond fibersfrom 4^(th) 20.5 μm production beam

Example 16

Example 16 was made in the same manner as Example 15 with the exceptionthat the bonding pattern B was used. The total basis weight measurementfor Example 16 was the same total basis weight as Comparative Example14. In addition, the individual S/M/M/S layers of Example 16 had thesame basis weight calculations as Comparative Example 14, shown in Table7. The average fiber dimension of the fibers made from beams 1, 2, 3,and 4 in Example 16 were measured using Fiber Dimension Test Method 1and were the same as Example 15, shown above in Table 8.

Comparative Example 17

Comparative Example 17 was produced on a line having a single productionbeam fitted with a spinneret having capillaries with around-cross-sectional geometry having a dimension d1 of 0.6 mm and anaspect ratio of 1.0:1.0. Comparative Example 17, thus, included a singlespunbond layer including round-shaped spunbond fibers extruded from aisotactic homopolymer polypropylene resin having a MFR of about 35g/10min. The round-shaped spunbond fibers of Comparative Example 17 wereproduced at a throughout of about 128 kg per hours per meter width ofthe die productive area (kg/h/m). The round-shaped spunbond layer wasbonded using an embossed roll having a bonding pattern known as Design#6396 provided by Overbeck & Co. GmbH of Krefeld, Germany. This patternconsisted of square diamond shaped pins having sides each having alength of 0.75 mm. The pins are present at a density of about 33.9pin/cm², providing a pin contact surface area that covers about 19% ofthe total bonding surface of the embossed portion of the roll.Comparative Example 17 had a basis weight of about 17.5 gsm and includedround-shaped spunbond fibers having a denier of about 1.9 based ondimension d1 of about 17.3 microns.

Example 18

Example 18 was also produced from the same polymer resin as ComparativeExample 17 on the same production line, the same beam and samethroughput, with the exception that production beam included a spinneretwith capillaries having a ribbon-shaped cross-sectional geometry that issimilar to the capillaries used for Sample 7-12 and 15-16. The resultingfabric included a ribbon-shaped spunbond layer of Example 18 was bondedwith same embossing diamond pattern as Comparative Example 17 and had abasis weight calculation measured at about 17 gsm. The ribbon-shapedspunbond layer of Example 18 included ribbon-shaped spunbond fibershaving a dimension d1 of 39 microns and a dimension d2 of 11 microns,measured according to Fiber Dimension Test Method 2 providing an aspectratio of 3.55:1.

The processing conditions for Comparative Examples and Examples 1-16 areshown in Table 9. The test results for Comparative Examples and Examples1, 3, 5, 7,9, 11, 13 and 15 made using bonding pattern A are shown inTable 10. The test results for Comparative Examples and Examples 2, 4,6, 8, 10, 12, 14 and 16 made using bonding pattern B are shown in Table11. The test results for Comparative Example 17 and Example 18 are shownin Table 12.

Discussion of Results

When a nonwoven fabric is intended to be used in a personal hygieneproduct or as a component of a personal hygiene product, an importantcharacteristic is its resistance to penetration by body exudates. Thosebody exudates are often of low surface tension due to their organiccontent; examples are runny bowel movement, blend of runny bowelmovement and urine (e.g., such a blend is projected to have a 32 mN/msurface tension, as taught in U.S. Pat. No. 7,626,073 column 9, lines9-12), or urine contaminated with lotion or other body exudates likeblood or menstrual fluids. Therefore, a way to assess the liquid barriercapability of nonwoven fabric is to test them using the LSTST testdescribed above. For such a nonwoven fabric, it is therefore desirableto achieve the highest LSTST-Time or the lowest LSTST-Flow possible. Itis also desirable that such personal hygiene product is comfortable andbreathable and thus, that the nonwoven fabric used in the personalhygiene product allows hot air and vapor moisture to pass through thenonwoven fabric. It is generally accepted that more movement of hot airand vapor moisture can occur through nonwoven fabrics having higher airpermeability. However, for a typical nonwoven fabric having a layeredS/M/M/S construction, an increase in air permeability is usuallyachieved at the expense of the liquid barrier performance or LSTST-Flow.

Comparative Examples 1-6 and Examples 7-12 had a total fabric basisweight measurement of about 13 gsm and included a meltblown fibercontent of about 10% by weight of the total fabric basis weight. TheS/M/M/S layered construction of Comparative Examples 1-6 and Examples7-12 was typical of what is used as barrier leg cuff in baby diaper oradult incontinence products (as shown, e.g., in U.S. Pat. Appin. Publ.No. 2005/0215155 A1). The performance of Comparative Examples 1-6 andExamples 7-12 indicate the influence of the cross-section geometry andaspect ratio of the spunbond fibers and DCD on liquid barrierperformance and air permeability. Comparative Examples 1-6 and Examples7-12 were tested and measurements for air permeability and LSTST-Flowwere obtained. The resulting measurements were used to calculate theFlow Ratio. The results are shown in Tables 10 and 11.

It was observed that by comparing Comparative Example 1 with Example 7and comparing Comparative Examples 2 with Example 8, that Examples 7 and8, which included two ribbon-shaped spunbond layers had a substantiallylower Flow Ratio than equivalent Comparative Examples 1 and 2, whichincluded two round-shaped spunbond layers. In addition, the comparisonof Comparative Example 1 with Example 7 and the comparison ofComparative Example 2 with Example 8 also indicate that a lower FlowRatio represents a more favorable balance between liquid barrierproperty and air permeability. Specifically, where air permeability isequal between nonwoven fabrics, a nonwoven fabric with a lower FlowRatio will exhibit a better resistance to flow of low surface tensionliquid. The same observation was made while comparing ComparativeExample 3 with Example 9 and while comparing Comparative Examples 4 andExample 10.

It is noted that the observation that a lower Flow Ratio represents amore favorable balance between liquid barrier property and airpermeability described above in nonwoven fabrics that included tworibbon-shaped spunbond layers did not appear to materialize whencomparing Comparative Example 5 with Example 11 and when comparingComparative Examples 6 with Example 12. It is thought that the lowerFlow Ratio results observed for Examples 7-10, which included meltblownlayers formed using production beams having a DCD of 110 mm and 150 mm,was due to ability of meltblown fibers formed at the lower DCD to form amore compact and better supported web when deposited on a firstribbon-shaped spunbond layer and covered by a second ribbon-shapedspunbond layer. In particular, it is thought that the meltblown fibersform a more compact web when disposed between the two ribbon-shapedspunbond layers than when the meltblown fibers are disposed between tworound-shaped spunbond layers. The more compact web that is formed shouldresult in a slight downward shift in pore size distribution for the highside of the pore size distribution curve at 10% and 25% cumulativefilter flows, indicating a lower number of larger pores or a lowerfraction of larger pores in the pore distribution curve. The morecompact web is also thought to lower the ability for the liquid totravel within the X-Y plane of the meltblown layer after the liquidenters the fabric along the Z-axis, which is oriented perpendicular to amajor surface of the fabric. In general, a correlation was observedbetween the improvement or degradation of the Flow Ratio and thedifference in pore size measured at 10% and 25% cumulative filter flow(see, e.g., FIGS. 6 and 7). It is thought that the presence of largerpores have the greatest impact on the flow of low surface tension liquidthrough the fabric. Accordingly, as the number of larger poresincreases, the LSTST-Flow measurement also increases.

It also was observed that the difference in Flow Ratio, as well as thereduction in pore size at 10% and 25% cumulative filter flow, becomesmore favorable as the DCD is reduced. These results are shown in Tables10 and 11. Based on these observations, it is thought that the level ofenergy at which the meltblown fibers are projected toward the underlyinglayer influence the liquid barrier performance of a fabric. At a lowerDCD, a more compact web is formed by meltblown fiber than at high DCD,which is attributed to the difference in kinetic energy remaining whenthe fibers reach the forming surface. It was thought that at the processconditions used for Examples 11-12, including meltblown fibers formed ata DCD of 190 mm, the kinetic energy of the meltblown fibers reachingunderlying ribbon-shaped spunbond layer was so low or attenuated that itformed a bulkier and less uniform web that did not benefit from theflatter surface offered by the first ribbon-shaped spunbond layers ofExamples 7-10.

Comparative Examples 13-14 and Examples 15-16 were compared toinvestigate the impact of the cross-sectional geometry and aspect ratioof the spunbond fibers and bonding pattern on heavier nonwoven fabricsthat contain a higher percentage of meltblown fibers. By comparingComparative Example 13 with Example 15 and Comparative Examples 14 withExample 16, no significant benefit was observed in regard to Flow Ratio.It is thought that as the amount of meltblown fiber was increased, theimpact of the cross-sectional geometry and aspect ratio of the spunbondfibers is diminished.

It was observed from the data collected in Tables 10 and 11 forComparative Examples 1 to 6, Example 7 to 12, Comparative Examples 13-14and Example 15-16, that the relative benefit in Flow Ratio attributed tothe use of ribbon-shaped spunbond fibers rather than round-shapedspunbond fibers for was not largely influence by the bonding patternused.

In another experiment, Comparative Example 17 and Example 18 wereproduced to compare spunbond layers made from round-shaped spunbondfibers with spunbond layers made from ribbon-shaped spunbond fibers. Theair permeability, LSTST, and flow ratio results for Comparative Example17 and Example 18 are shown in Table 12. Example 18 did not exhibit anadvantage in regard to Flow Ratio when compared to Comparative Example17. Based on this observation, it is believed that the lower Flow Ratiorepresenting a more favorable balance between liquid barrier propertyand air permeability discussed above is not due to the ribbon-shapedspunbond fibers or layers alone, but is rather due to the combination ofribbon-shaped spunbond layer and a layer of meltblown fibers.

The results have shown the unexpected findings that nonwoven fabrics canbenefit in regard to Flow Ratio by incorporating ribbon-shaped spunbondfibers rather than round-shaped spunbond fibers in a layeredconstruction with meltblown layers. In addition, the results have shownthe unexpected findings that nonwoven fabrics can benefit in regard toFlow Ratio when the meltblown layer is designed to provide a nonwovenfabric that has a pore size measured at 10% of cumulative filter flow ofno more than about 27 microns. Moreover, it is believed that providing anonwoven fabric with a total content of meltblown fibers that istailored to avoid forming an excessively tight structure can enhance thebenefits of ribbon-shaped spunbond layers made of ribbon-shaped spunbondfibers.

TABLE 9 Comparative Examples and Examples 1 & 2 7 & 8 3 & 4 9 & 10 5 & 611 & 12 13 & 14 15 & 16 Shape of spunbond Round Ribbon Round RibbonRound Ribbon Round Ribbon fibers Throughput for 1^(st) and Kg/h (1)169/171 167/171 169/171 167/171 169/171 167/171 174/176 172/176 4^(th)beams producing the spunbond fiber layers Throughput for 2^(nd) and Kg/h(1) 18/19 19/19 18/19 19/19 18/19 19/19 43/43 43/43 3^(rd) beamsproducing the meltblown fibers Line speed meters/min 449 449 449 449 449449 150 150 Distance from die to mm 110/110 110/110 150/150 150/150190/190 190/190 180/200 180/200 collector (DCD for meltblown 2^(nd) and3^(rd) beams) (1) The productive length of the spinneret was about 1.1meter

TABLE 10 TEST RESULTS FOR COMAPRATIVE EXAMPLES AND EXAMPLES MADE USINGTHE BONDING PATTERN A Comparative Examples and Examples 1 7 3 9 5 11 1315 Shape of spunbond fibers Round Ribbon Round Ribbon Round Ribbon RoundRibbon DCD for the meltblown 2^(nd) and 110/110 110/110 150/150 150/150190/190 190/190 180/200 180/200 3^(rd) beams (mm) Basis weight (gsm)13.2 13.5 13.1 13.8 13 12.9 45.5 45.5 Air Permeability for a single ply40 37.5 50 50 56 58 7.25 6.35 (m³/m²/min) LSTST-Time measured on — — — —— — 38 42 single ply sample (second) LSTST-Flow for single-ply — — — — —— 0.132 0.119 measurement (ml/sec) Flow Ratio for single-Ply — — — — — —0.018 0.019 measurement Difference in Flow Ratio for 3% ribbon vs. roundfilament samples tested as single ply Air Permeability for two plies21.5 17 24 20.5 27.5 22.5 — — (m³/m²/min) LSTST-Time measured on two 9.414.2 9.4 12.8 9.1 10.1 — — plies of sample(second) LSTST-Flow fortwo-plies 0.53 0.35 0.53 0.39 0.55 0.50 — — measurement (ml/sec) FlowRatio for two-plies 0.0247 0.0207 0.0222 0.0191 0.0200 0.0220 — —measurement Difference in Flow Ratio for −16% −14% 10% ribbon vs. roundfilament samples tested as two plies Pore size at 10% cumulative 16 14.522 19 26 30 8.5 9 filter flow (micron) Pore size at 25% cumulative 14.513.5 19 16 20 23 7.5 8 filter flow (micron)

TABLE 11 TEST RESULTS FOR COMPARATIVE EXAMPLES AND EXAMPLES MADE USINGTHE BONDING PATTERN B Comparative Examples and Examples 2 8 4 10 6 12 1416 Shape of spunbond fibers Round Ribbon Round Ribbon Round Ribbon RoundRibbon DCD for the meltblown 2^(nd) and 110/110 110/110 150/150 150/150190/190 190/190 180/200 180/200 3^(rd) beams (mm) Basis weight (gsm)13.2 13.5 13.1 13.8 13 12.9 45.5 45.5 Air Permeability for a single ply38 33 46 39 53 48.5 6.6 6.2 (m³/m²/min) LSTST-Time measured on — — — — —— 32 34 single ply sample (second) LSTST-Flow for single-ply — — — — — —0.156 0.147 measurement (ml/sec) Flow Ratio for single-Ply — — — — — —0.024 0.024 measurement Difference in Flow Ratio for 0% ribbon vs. roundfilament samples tested as single ply Air Permeability for two plies19.5 15.5 22 18 25.5 19 3.1 2.45 (m³/m²/min) LSTST-Time measured on two10.2 15.1 9.9 13.8 9.2 11 plies of sample(second) LSTST-Flow fortwo-plies 0.49 0.33 0.51 0.36 0.54 0.45 measurement (ml/sec) Flow Ratiofor two-plies 0.0251 0.0214 0.0230 0.0201 0.0213 0.0239 measurementDifference in Flow Ratio for −15% −12% 12% ribbon vs. round filamentsamples tested as two plies Pore size at 10% cumulative 14.5 14.5 25 2122 35 8 9.2 filter flow (micron) Pore size at 25% cumulative 13.5 13 1916.5 19 27 7.1 8.1 filter flow (micron)

TABLE 12 Comparative Example and Example 17 18 Shape of spunbond fibersRound Ribbon Basis weight (gsm) Air Permeability for a single ply 235165 (m³/m²/min) Air Permeability for two plies (m³/m²/min) 125 90LSTST-Time measured on two plies of 4 5.2 sample(second) LSTST-Flow fortwo-plies measurement 1.25 0.96 (ml/sec) Flow Ratio for two-pliesmeasurement 0.0100 0.0107 Difference in ratio for ribbon vs. round 7%filament samples tested as two plies

Unless indicated otherwise, all amounts, percentages, ratios and thelike used herein are by weight. When an amount, concentration, or othervalue or parameter is given as either a range, preferred range, or alist of upper preferable values and lower preferable values, this is tobe understood as specifically disclosing all ranges formed from any pairof any upper range limit or preferred value and any lower range limit orpreferred value, regardless of whether ranges are separately disclosed.Where a range of numerical values is recited herein, unless otherwisestated, the range is intended to include the endpoints thereof, and allintegers and fractions within the range. It is not intended that thescope of the invention be limited to the specific values recited whendefining a range.

Although the invention herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent invention. It will be apparent to those skilled in the art thatvarious modifications and variations can be made to the method andapparatus of the present invention without departing from the spirit andscope of the invention. Thus, it is intended that the present inventioninclude modifications and variations that are within the scope of theappended claims and their equivalents.

1-20. (canceled)
 21. A method of forming a nonwoven fabric, comprising:(i) providing or forming a first spunbond layer comprising a firstplurality of ribbon-shaped continuous filaments; (ii) directlydepositing a meltblown layer onto the first spunbond layer from a diehaving a die-to-collector distance from about 110 mm to about 150 mm;(iii) depositing a second spunbond layer comprising a second pluralityof ribbon-shaped continuous filaments directly onto the meltblown layer;and (iv) consolidating the first spunbond layer, the meltblown layer,and the second spunbond layer together to form the nonwoven fabric. 22.The method of claim 21, wherein the meltblown layer comprises meltblownfibers in an amount of at least 0.1% by weight of the nonwoven fabricand not greater than about 40% by weight of the nonwoven fabric.
 23. Themethod of claim 21, wherein the meltblown layer has a basis weight nogreater than 5 gsm.
 24. The method of claim 21, wherein at least one ofthe first spunbond layer, the second spunbond layer, and the meltblownlayer comprise polypropylene.
 25. The method of claim 24, wherein eachof the first spunbond layer, the second spunbond layer, and themeltblown layer comprises polypropylene.
 26. The method of claim 21,wherein the nonwoven fabric contains less than about 10% by weightnon-ribbon shaped spunbond fibers, and wherein the nonwoven fabric has abasis weight of at least about 8 gsm and not greater than about 40 gsm.27. The method of claim 21, wherein the meltblown layer consists of (i)from 1% to 10% by weight of non-ribbon shaped meltblown fibers, and (ii)ribbon-shaped meltblown fibers.
 28. The method of claim 21, wherein thenonwoven fabric has a pore size of about 14.5 microns to less than orequal to about 21 microns when measured at 10% of cumulative filterflow.
 29. The method of claim 21, wherein the nonwoven fabric has a lowsurface tension liquid strike through flow of less than 0.9 ml persecond, an air permeability of at least 10 m³/m²/min. and a ratio of lowsurface tension liquid strike through flow to air permeability ofgreater than or equal to 0.016 and less than or equal to 0.021.
 30. Themethod of claim 21, wherein at least one of the first plurality ofribbon-shaped continuous filaments and the second plurality ofribbon-shaped continuous filaments comprises fibers having across-section with an aspect ratio of at least 2.5:1 and no great thanabout 7:1.
 31. The method of claim 21, wherein the depositing ameltblown layer comprises depositing a first meltblown layer directlyonto the first spunbond layer from a first die having a firstdie-to-collector distance from about 110 mm to about 150 mm anddepositing at least a second meltblown layer directly onto the firstmeltblown layer from a second die having a second die-to-collectordistance from about 110 mm to about 150 mm.
 32. The method of claim 21,wherein consolidating the first spunbond layer, the meltblown layer, andthe second spunbond layer together to form the nonwoven fabric comprisesa thermal bonding operation.
 33. The method of claim 32, wherein thethermal bonding operation forms a plurality of discrete bond areas
 34. Anonwoven fabric, comprising: a first spunbond layer comprising a firstplurality of ribbon-shaped continuous filaments; a second spunbond layercomprising a second plurality of ribbon-shaped continuous filaments; anda meltblown layer disposed between the first spunbond layer and thesecond spunbond layer, wherein said meltblown layer has a basis weightof not greater than about 5 gsm; wherein the nonwoven fabric has a basisweight of at least 8 gsm and not greater than about 40 gsm, a lowsurface tension liquid strike through flow of less than 0.9 ml persecond, an air permeability of at least 10 m³/m²/min. and a ratio of lowsurface tension liquid strike through flow to air permeability ofgreater than or equal to 0.016 and less than or equal to 0.021; whereinthe meltblown layer has been deposited directly onto the secondribbon-shaped spunbond layer from at least one die having adie-to-collector distance from about 110 mm to about 150 mm.
 35. Thenonwoven fabric of claim 34, wherein the nonwoven fabric has a pore sizeof about 14.5 microns to less than or equal to about 21 microns whenmeasured at 10% of cumulative filter flow.
 36. The nonwoven fabric ofclaim 34, wherein at least one of the first spunbond layer and secondspunbond layer comprises fibers having a cross-section with an aspectratio of at least 2.5:1 and no great than about 7:1.
 37. The nonwovenfabric of claim 34, wherein the meltblown layer consists of (i) from 1%to 10% by weight of non-ribbon shaped meltblown fibers, and (ii)ribbon-shaped meltblown fibers
 38. The nonwoven fabric of claim 34,wherein the meltblown layer comprises multiple directly adjoiningmeltblown sub-layers.
 39. The nonwoven fabric of claim 34, wherein thenonwoven fabric contains less than about 10% by weight non-ribbon shapedspunbond fibers.
 40. The nonwoven fabric of claim 34, wherein the firstspunbond layer, the second spunbond layer, and the meltblown layer arebonded together by a plurality of discrete bond areas.